fix: crop save always JPEG q93 + save rotated view 1:1 (v1.4.1)

- Output extension is always .jpg regardless of source format (was: PNG in -> PNG out)
- Rotation now saved correctly: viewport grid resampled bilinearly in source
  space (was: unrotated bounding box copy)
- Quality 90 -> 93; l10n strings updated (JPEG 93)
- New: tool/crop_test.dart — pure-Dart end-to-end test (dart run tool/crop_test.dart)

lib/widgets/image_canvas.dart

@@ -5,6 +5,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 import '../l10n/app_localizations.dart';
+import '../services/crop_save_service.dart';
 
 class ImageCanvas extends StatefulWidget {
   final String filePath;
@@ -396,42 +397,28 @@ class ImageCanvasState extends State<ImageCanvas> {
     return _cachedMatrix;
   }
 
-  /// Viewport'un görünen bölgesini kaynak (tam çözünürlük) uzayına eşler.
-  /// [w]x[h] = gerçek dosya boyutu. Degrade durumda null.
-  Rect? cropSourceRect(int w, int h) {
+  /// Viewport'un gorunen bolgesinin tam cozunurluktaki eslemesi (crop_save_service'e).
+  /// Degrade durumda null.
+  CropViewParams? cropViewParams(int w, int h) {
     if (_vpSize.width <= 0 || _vpSize.height <= 0 || w <= 0 || h <= 0) return null;
-    final cx = _vpSize.width / 2, cy = _vpSize.height / 2;
-    final rad = -_angle * math.pi / 180;
-    final cos = math.cos(rad), sin = math.sin(rad);
-
-    Offset toSrc(Offset p) {
-      final double qx = (p.dx - _tx) / _sc, qy = (p.dy - _ty) / _sc;
-      final double rx = (_angle == 0) ? qx : (cos * (qx - cx) - sin * (qy - cy) + cx);
-      final double ry = (_angle == 0) ? qy : (sin * (qx - cx) + cos * (qy - cy) + cy);
-      final double k = _isFilled
-          ? math.max(_vpSize.width / w, _vpSize.height / h)
-          : math.min(_vpSize.width / w, _vpSize.height / h);
-      final double ox = (_vpSize.width - w * k) / 2, oy = (_vpSize.height - h * k) / 2;
-      return Offset((rx - ox) / k, (ry - oy) / k);
-    }
-
-    final corners = [
-      toSrc(Offset.zero),
-      toSrc(Offset(_vpSize.width, 0)),
-      toSrc(Offset(_vpSize.width, _vpSize.height)),
-      toSrc(Offset(0, _vpSize.height)),
-    ];
-    double xmin = double.infinity, xmax = -double.infinity;
-    double ymin = double.infinity, ymax = -double.infinity;
-    for (final c in corners) {
-      xmin = math.min(xmin, c.dx); xmax = math.max(xmax, c.dx);
-      ymin = math.min(ymin, c.dy); ymax = math.max(ymax, c.dy);
-    }
-    return Rect.fromLTRB(
-      xmin.clamp(0.0, w.toDouble()),
-      ymin.clamp(0.0, h.toDouble()),
-      xmax.clamp(0.0, w.toDouble()),
-      ymax.clamp(0.0, h.toDouble()),
+    final k = _isFilled
+        ? math.max(_vpSize.width / w, _vpSize.height / h)
+        : math.min(_vpSize.width / w, _vpSize.height / h);
+    final ox = (_vpSize.width - w * k) / 2, oy = (_vpSize.height - h * k) / 2;
+    return CropViewParams(
+      w: w,
+      h: h,
+      vw: _vpSize.width,
+      vh: _vpSize.height,
+      tx: _tx,
+      ty: _ty,
+      sc: _sc,
+      angleDeg: _angle,
+      cx: _vpSize.width / 2,
+      cy: _vpSize.height / 2,
+      k: k,
+      ox: ox,
+      oy: oy,
     );
   }