feat: crop save (save visible area at original resolution) v1.4.0

- Save visible area at original resolution as JPEG q90 (title bar button or Ctrl+S)
- Output name: original name + _HHmmss suffix; no overwrite, warning shown
- Active color effects baked in; rotation saves bounding box
- New: crop_save_service, l10n strings TR/EN, docs/plan-crop-save.md

lib/services/crop_save_service.dart

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+import 'dart:io';
+import 'dart:ui' show Rect;
+import 'package:image/image.dart' as img;
+import 'package:path/path.dart' as p;
+
+class CropSaveError implements Exception {
+  final String code;
+  const CropSaveError(this.code);
+
+  @override
+  String toString() => 'CropSaveError($code)';
+}
+
+class CropSaveService {
+  /// Tam çözünürlükte decode + EXIF yönünü gömme (engine görüntüsüyle tutarlı).
+  static Future<img.Image> load(String srcPath) async {
+    final bytes = await File(srcPath).readAsBytes();
+    final src = img.decodeImage(bytes);
+    if (src == null) throw const CropSaveError('decode');
+    return img.bakeOrientation(src);
+  }
+
+  /// Hedef yol: `resim.jpg` -> `resim_143025.jpg` (çakışmada null).
+  static String? buildOutputPath(String srcPath) {
+    final ext = p.extension(srcPath);
+    final base = p.basenameWithoutExtension(srcPath);
+    final dir = p.dirname(srcPath);
+    final now = DateTime.now();
+    final hh = now.hour.toString().padLeft(2, '0');
+    final mm = now.minute.toString().padLeft(2, '0');
+    final ss = now.second.toString().padLeft(2, '0');
+    final candidate = p.join(dir, '${base}_$hh$mm$ss$ext');
+    return File(candidate).existsSync() ? null : candidate;
+  }
+
+  /// Crop + aktif renk matrisi + JPEG q90.
+  /// [matrix] 4x5 row-major renk matrisi (image_canvas ile aynı form, 0-255 alanı);
+  /// null = gömme yok.
+  static Future<String> saveCrop({
+    required String srcPath,
+    required img.Image source,
+    required Rect rect,
+    List<double>? matrix,
+  }) async {
+    final outPath = buildOutputPath(srcPath);
+    if (outPath == null) throw const CropSaveError('file_exists');
+
+    final iw = source.width, ih = source.height;
+    final x = rect.left.round().clamp(0, iw - 1);
+    final y = rect.top.round().clamp(0, ih - 1);
+    final w = rect.right.round().clamp(x + 1, iw) - x;
+    final h = rect.bottom.round().clamp(y + 1, ih) - y;
+    if (w <= 0 || h <= 0) throw const CropSaveError('empty_rect');
+
+    final crop = img.copyCrop(source, x: x, y: y, width: w, height: h);
+    // Çıktıda yön fiziksel — EXIF tag'ini temizle (çift dönüşü önler).
+    crop.exif.imageIfd.orientation = null;
+
+    if (matrix != null) _applyMatrix(crop, matrix);
+
+    final jpeg = img.JpegEncoder(quality: 90).encode(crop);
+    await File(outPath).writeAsBytes(jpeg);
+    return outPath;
+  }
+
+  /// Flutter'la aynı 0-255 alan/semantiğindeki 4x5 matrisi uygular.
+  static void _applyMatrix(img.Image image, List<double> m) {
+    for (final pixel in image) {
+      final r = pixel.r.toDouble(), g = pixel.g.toDouble(), b = pixel.b.toDouble();
+      pixel.r = (m[0] * r + m[1] * g + m[2] * b + m[4]).clamp(0, 255).round();
+      pixel.g = (m[5] * r + m[6] * g + m[7] * b + m[9]).clamp(0, 255).round();
+      pixel.b = (m[10] * r + m[11] * g + m[12] * b + m[13]).clamp(0, 255).round();
+    }
+  }
+}