feat: persist fill/fit view mode in window.json (v1.5.0)

The double-click fill/fit mode was hardcoded (image_canvas: _isFilled = true) and
reset on every image change, so it never survived a restart. It is now stored as
"filled" in window.json and restored on launch and on image switch.

WindowPersistence.saveSync() now merges with the existing file, otherwise the
startup/move/resize geometry writes would drop the mode key.

Also: version 1.5.0, CHANGELOG entry, dist/ ships imajviewer_1.5.0_amd64.deb
(replaces 1.4.2).

lib/services/window_persistence.dart

@@ -15,28 +15,59 @@ class WindowPersistence {
     return File('$dir/window.json');
   }
 
+  /// Görüntü ekran modu: true = pencereyi kapla (cover), false = sığdır (contain).
+  /// Anahtar yoksa/bozuksa true (eski davranış).
+  static bool get filled {
+    final v = _read()?['filled'];
+    return v is bool ? v : true;
+  }
+
+  /// Sadece modu günceller; x/y/w/h korunur.
+  static void saveFilled(bool value) => _write({'filled': value});
+
   /// Save window rect synchronously (safe to call before destroy).
   static void saveSync({
     required Offset position,
     required Size size,
   }) {
-    final file = _configFile;
-    file.parent.createSync(recursive: true);
-    file.writeAsStringSync(jsonEncode({
+    _write({
       'x': position.dx.toInt(),
       'y': position.dy.toInt(),
       'width': size.width.toInt(),
       'height': size.height.toInt(),
-    }));
+    });
+  }
+
+  /// Dosyayı oku (yok/bozuksa null).
+  static Map<String, dynamic>? _read() {
+    final file = _configFile;
+    if (!file.existsSync()) return null;
+    try {
+      return jsonDecode(file.readAsStringSync()) as Map<String, dynamic>;
+    } catch (_) {
+      return null;
+    }
+  }
+
+  /// Verilen anahtarları yaz; dosyadaki diğer anahtarlar korunur.
+  static void _write(Map<String, dynamic> values) {
+    try {
+      final file = _configFile;
+      file.parent.createSync(recursive: true);
+      final data = _read() ?? <String, dynamic>{};
+      data.addAll(values);
+      file.writeAsStringSync(jsonEncode(data));
+    } catch (_) {
+      // Disk hatası uygulamayı durdurmasın.
+    }
   }
 
   /// Restore saved window rect. Returns null if no saved config.
   static ({Offset position, Size size})? restore() {
-    final file = _configFile;
-    if (!file.existsSync()) return null;
+    final data = _read();
+    if (data == null) return null;
 
     try {
-      final data = jsonDecode(file.readAsStringSync()) as Map<String, dynamic>;
       final x = (data['x'] as num?)?.toDouble() ?? 0;
       final y = (data['y'] as num?)?.toDouble() ?? 0;
       final w = (data['width'] as num?)?.toDouble() ?? 1280;

lib/widgets/image_canvas.dart

@@ -6,6 +6,7 @@ import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 import '../l10n/app_localizations.dart';
 import '../services/crop_save_service.dart';
+import '../services/window_persistence.dart';
 
 class ImageCanvas extends StatefulWidget {
   final String filePath;
@@ -15,7 +16,7 @@ class ImageCanvas extends StatefulWidget {
 }
 
 class ImageCanvasState extends State<ImageCanvas> {
-  bool _isFilled = true;
+  bool _isFilled = WindowPersistence.filled;
   final GlobalKey _imageKey = GlobalKey();
   double _tx = 0, _ty = 0, _sc = 1.0;
   Size _vpSize = Size.zero;
@@ -199,7 +200,7 @@ class ImageCanvasState extends State<ImageCanvas> {
   }
 
   void _resetView() {
-    _tx = 0; _ty = 0; _sc = 1.0; _isFilled = true;
+    _tx = 0; _ty = 0; _sc = 1.0; _isFilled = WindowPersistence.filled;
     _angle = 0; _contrast = 1.0; _saturation = 1.0; _brightness = 0;
     _usingFullRes = false;
     _imageSize = Size.zero;
@@ -209,6 +210,7 @@ class ImageCanvasState extends State<ImageCanvas> {
   void _toggleFillFit() {
     _isFilled = !_isFilled; _tx = 0; _ty = 0; _sc = 1.0;
     _angle = 0; _contrast = 1.0; _saturation = 1.0; _brightness = 0;
+    WindowPersistence.saveFilled(_isFilled);
     _markRenderDirty();
   }