feat: letterbox-aware clamp, full-frame image, fit/fill zoom fix

- image_canvas.dart:
  - Fill mod: viewport tabanli clamp (_tx=0'da kilit)
  - Fit mod: RenderBox ile resmin gercek render boyutuna gore clamp
  - Letterbox offset (offX/offY) hesaba katilarak resmin kenarlarina kadar pan
  - Zoom-to-cursor dogru calisiyor (alignment: topLeft ile)
  - Min scale 1.0 (her iki modda da)
  - Overflow durumunda lo/hi reversed clamp (goruntu disari kacmaz)
- viewer_screen.dart: image alani top:24 -> top:0 (tam cerceve)
- install.sh: release -> debug bundle path (gelistirme)

lib/screens/viewer_screen.dart

@@ -119,28 +119,36 @@ class _ViewerScreenState extends State<ViewerScreen> with WindowListener {
             child: Stack(
               children: [
                 Positioned(
-                  top: 24,
+                  top: 0,
                   left: 0,
                   right: 0,
                   bottom: 0,
                   child: Container(color: const Color(0xFF1a1a1a)),
                 ),
-                Container(
-                  color: Colors.transparent,
-                  child: _hasImages
-                      ? ImageCanvas(filePath: ImageManager.instance.currentImagePath)
-                      : const Center(
-                          child: Column(
-                            mainAxisSize: MainAxisSize.min,
-                            children: [
-                              Icon(Icons.image, size: 64, color: Colors.white24),
-                              SizedBox(height: 16),
-                              Text('Resimleri buraya sürükleyin\nveya Ctrl+O ile açın',
-                                  textAlign: TextAlign.center,
-                                  style: TextStyle(color: Colors.white38, fontSize: 16)),
-                            ],
+                Positioned(
+                  top: 0,
+                  left: 0,
+                  right: 0,
+                  bottom: 0,
+                  child: Container(
+                    color: Colors.transparent,
+                    child: _hasImages
+                        ? ImageCanvas(
+                            filePath: ImageManager.instance.currentImagePath,
+                          )
+                        : const Center(
+                            child: Column(
+                              mainAxisSize: MainAxisSize.min,
+                              children: [
+                                Icon(Icons.image, size: 64, color: Colors.white24),
+                                SizedBox(height: 16),
+                                Text('Resimleri buraya sürükleyin\nveya Ctrl+O ile açın',
+                                    textAlign: TextAlign.center,
+                                    style: TextStyle(color: Colors.white38, fontSize: 16)),
+                              ],
+                            ),
                           ),
-                        ),
+                  ),
                 ),
                 const CustomTitleBar(),
                 if (_isDragging)

lib/widgets/image_canvas.dart

@@ -4,160 +4,171 @@ import 'package:flutter/gestures.dart';
 
 class ImageCanvas extends StatefulWidget {
   final String filePath;
-
   const ImageCanvas({super.key, required this.filePath});
-
   @override
   State<ImageCanvas> createState() => _ImageCanvasState();
 }
 
 class _ImageCanvasState extends State<ImageCanvas> {
-  late TransformationController _controller;
-  double _currentScale = 1.0;
-  bool _isFilled = true; // varsayılan: ekranı doldur
+  bool _isFilled = true;
+  final GlobalKey _imageKey = GlobalKey();
+  double _tx = 0, _ty = 0, _sc = 1.0;
+  Size _vpSize = Size.zero;
 
-  @override
-  void initState() {
-    super.initState();
-    _controller = TransformationController();
-    _controller.addListener(_onTransformChanged);
-  }
-
-  @override
-  void didUpdateWidget(ImageCanvas oldWidget) {
-    super.didUpdateWidget(oldWidget);
-    if (oldWidget.filePath != widget.filePath) {
-      _resetView();
+  void _clamp() {
+    if (_vpSize.width <= 0 || _vpSize.height <= 0) return;
+    if (_isFilled) {
+      // Fill mode: viewport tabanli clamp
+      final double w = _vpSize.width * _sc;
+      final double h = _vpSize.height * _sc;
+      if (w >= _vpSize.width) {
+        if (_tx > 0) _tx = 0;
+        else if (_tx + w < _vpSize.width) _tx = _vpSize.width - w;
+      } else { if (_tx != 0) _tx = 0; }
+      if (h >= _vpSize.height) {
+        if (_ty > 0) _ty = 0;
+        else if (_ty + h < _vpSize.height) _ty = _vpSize.height - h;
+      } else { if (_ty != 0) _ty = 0; }
+      return;
+    }
+    // Fit mode: resmin gercek boyutuna gore clamp (letterbox dahil)
+    double m = 0, n = 0;
+    double w = _vpSize.width * _sc;
+    double h = _vpSize.height * _sc;
+    final box = _imageKey.currentContext?.findRenderObject() as RenderBox?;
+    if (box != null && box.hasSize && box.size.width > 0) {
+      final Size img = box.size;
+      m = (_vpSize.width - img.width) / 2;
+      n = (_vpSize.height - img.height) / 2;
+      w = img.width * _sc;
+      h = img.height * _sc;
+    }
+    if (w >= _vpSize.width) {
+      final double lo = -m * _sc;
+      final double hi = _vpSize.width - m * _sc - w;
+      if (lo <= hi) {
+        if (_tx < lo) _tx = lo;
+        if (_tx > hi) _tx = hi;
+      } else {
+        if (_tx < hi) _tx = hi;
+        if (_tx > lo) _tx = lo;
+      }
+    } else {
+      final double lo = -m * _sc;
+      final double hi = _vpSize.width - m * _sc - w;
+      if (_tx < lo) _tx = lo;
+      if (_tx > hi) _tx = hi;
+    }
+    if (h >= _vpSize.height) {
+      final double lo = -n * _sc;
+      final double hi = _vpSize.height - n * _sc - h;
+      if (lo <= hi) {
+        if (_ty < lo) _ty = lo;
+        if (_ty > hi) _ty = hi;
+      } else {
+        if (_ty < hi) _ty = hi;
+        if (_ty > lo) _ty = lo;
+      }
+    } else {
+      final double lo = -n * _sc;
+      final double hi = _vpSize.height - n * _sc - h;
+      if (_ty < lo) _ty = lo;
+      if (_ty > hi) _ty = hi;
     }
   }
 
-  void _resetView() {
-    _controller.value = Matrix4.identity();
-    _currentScale = 1.0;
-    _isFilled = true;
-  }
-
-  void _onTransformChanged() {
-    _currentScale = _controller.value.getMaxScaleOnAxis();
-  }
-
-  void _toggleFillFit() {
-    setState(() {
-      _isFilled = !_isFilled;
-      _controller.value = Matrix4.identity();
-      _currentScale = 1.0;
-    });
-  }
-
-  void _handleDoubleTap() {
-    _toggleFillFit();
-  }
-
-  void _handleScroll(PointerScrollEvent event) {
-    final renderBox = context.findRenderObject() as RenderBox?;
-    if (renderBox == null) return;
-
-    final localPosition = renderBox.globalToLocal(event.position);
-
-    final delta = event.scrollDelta.dy;
-    final scaleFactor = delta < 0 ? 1.1 : 1 / 1.1;
-
-    final newScale = (_currentScale * scaleFactor).clamp(0.1, 10.0);
-    if (newScale <= 0.1 || newScale >= 10.0) return;
-
-    final actualScale = newScale / _currentScale;
-
-    // Fare altındaki child-space noktayı hesapla
-    final matrix = _controller.value;
-    final tx = matrix.getTranslation().x;
-    final ty = matrix.getTranslation().y;
-
-    final childX = (localPosition.dx - tx) / _currentScale;
-    final childY = (localPosition.dy - ty) / _currentScale;
-
-    // controller * zoomAroundPoint sırasıyla uygula
-    final newMatrix = Matrix4.copy(_controller.value)
-      // ignore: deprecated_member_use
-      ..translate(childX, childY)
-      // ignore: deprecated_member_use
-      ..scale(actualScale)
-      // ignore: deprecated_member_use
-      ..translate(-childX, -childY);
-
-    _controller.value = newMatrix;
-  }
-
   @override
-  void dispose() {
-    _controller.removeListener(_onTransformChanged);
-    _controller.dispose();
-    super.dispose();
+  void didUpdateWidget(ImageCanvas old) {
+    super.didUpdateWidget(old);
+    if (old.filePath != widget.filePath) _resetView();
+  }
+  void _resetView() {
+    setState(() { _tx = 0; _ty = 0; _sc = 1.0; _isFilled = true; _vpSize = Size.zero; });
+  }
+  void _toggleFillFit() {
+    setState(() { _isFilled = !_isFilled; _tx = 0; _ty = 0; _sc = 1.0; _vpSize = Size.zero; });
+  }
+  void _handleDoubleTap() => _toggleFillFit();
+
+  void _handleScroll(PointerScrollEvent e) {
+    if (_vpSize.width <= 0 || _vpSize.height <= 0) return;
+    final double vx = e.localPosition.dx;
+    final double vy = e.localPosition.dy;
+    final double cx = (vx - _tx) / _sc;
+    final double cy = (vy - _ty) / _sc;
+    const double factor = 1.1;
+    final double rawSc = _sc * (e.scrollDelta.dy < 0 ? factor : 1.0 / factor);
+    final double newSc = rawSc.clamp(1.0, 10.0);
+    _tx = _tx + cx * _sc - cx * newSc;
+    _ty = _ty + cy * _sc - cy * newSc;
+    _sc = newSc;
+    _clamp();
+    setState(() {});
+  }
+
+  void _onPanUpdate(DragUpdateDetails d) {
+    _tx += d.delta.dx;
+    _ty += d.delta.dy;
+    _clamp();
+    setState(() {});
+  }
+
+  Widget _buildImage() {
+    return Image.file(
+      key: _imageKey,
+      File(widget.filePath),
+      fit: _isFilled ? BoxFit.cover : BoxFit.contain,
+      filterQuality: FilterQuality.high,
+      errorBuilder: (_, _, _) => _errorWidget(),
+    );
   }
 
   @override
   Widget build(BuildContext context) {
     return LayoutBuilder(
       builder: (context, constraints) {
-        return Listener(
-          onPointerSignal: (event) {
-            if (event is PointerScrollEvent) {
-              _handleScroll(event);
-            }
-          },
-          child: GestureDetector(
-            onDoubleTap: _handleDoubleTap,
-            child: InteractiveViewer(
-              transformationController: _controller,
-              boundaryMargin: const EdgeInsets.all(double.infinity),
-              minScale: 0.1,
-              maxScale: 10.0,
-              panEnabled: true,
-              scaleEnabled: false,
-              child: _isFilled
-                  ? SizedBox.expand(
-                      child: Image.file(
-                        File(widget.filePath),
-                        fit: BoxFit.cover,
-                        filterQuality: FilterQuality.high,
-                        errorBuilder: (context, error, stackTrace) {
-                          return const Center(
-                            child: Column(
-                              mainAxisSize: MainAxisSize.min,
-                              children: [
-                                Icon(Icons.broken_image, size: 48, color: Colors.white38),
-                                SizedBox(height: 8),
-                                Text('Resim yüklenemedi',
-                                    style: TextStyle(color: Colors.white38)),
-                              ],
-                            ),
-                          );
-                        },
-                      ),
-                    )
-                  : Center(
-                      child: Image.file(
-                        File(widget.filePath),
-                        fit: BoxFit.contain,
-                        filterQuality: FilterQuality.high,
-                        errorBuilder: (context, error, stackTrace) {
-                          return const Center(
-                            child: Column(
-                              mainAxisSize: MainAxisSize.min,
-                              children: [
-                                Icon(Icons.broken_image, size: 48, color: Colors.white38),
-                                SizedBox(height: 8),
-                                Text('Resim yüklenemedi',
-                                    style: TextStyle(color: Colors.white38)),
-                              ],
-                            ),
-                          );
-                        },
-                      ),
+        _vpSize = constraints.biggest;
+        _clamp();
+        return SizedBox.expand(
+          child: Stack(
+            children: [
+              ClipRect(
+                child: GestureDetector(
+                  onDoubleTap: _handleDoubleTap,
+                  onPanUpdate: _onPanUpdate,
+                  child: Listener(
+                    onPointerSignal: (event) {
+                      if (event is PointerScrollEvent) _handleScroll(event);
+                    },
+                    child: Transform(
+                      alignment: Alignment.topLeft,
+                      transform: Matrix4.identity()
+                        ..translate(_tx, _ty)
+                        ..scale(_sc),
+                      child: _isFilled
+                          ? SizedBox.expand(child: _buildImage())
+                          : Center(child: _buildImage()),
                     ),
-            ),
+                  ),
+                ),
+              ),
+            ],
           ),
         );
       },
     );
   }
+
+  Widget _errorWidget() {
+    return const Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Icon(Icons.broken_image, size: 48, color: Colors.white38),
+          SizedBox(height: 8),
+          Text('Resim yüklenemedi', style: TextStyle(color: Colors.white38)),
+        ],
+      ),
+    );
+  }
 }