feat: jfif/jpe/wbmp format destegi, pencere cascade yerlesimi, konum kaydi duzeltmesi

- file_handler/image_manager: jfif, jpe, wbmp uzantilari
- .desktop + install.sh MimeType: image/vnd.wap.wbmp eklendi
- main.dart: yeni pencere oncekinin saginda acilir (screen_retriever ile ekran tespiti)
- viewer_screen: 2sn polling kaldirildi, konum kaydi tek akisa oturtuldu (acilis + move/resize debounce + close senkron)
- dist/rebuild-deb.sh: .desktop kaynaktan kopyalanir (MimeType/StartupWMClass guncel kalir)
- .deb guncellendi, docs: session-2026-08-03 + plan dokumanlari

lib/services/file_handler.dart

@@ -6,7 +6,7 @@ class FileHandler {
   static Future<void> openFileDialog() async {
     final result = await FilePicker.platform.pickFiles(
       type: FileType.custom,
-      allowedExtensions: ['png', 'jpg', 'jpeg', 'webp', 'bmp', 'gif'],
+      allowedExtensions: ['png', 'jpg', 'jpeg', 'jfif', 'jpe', 'webp', 'bmp', 'gif', 'wbmp'],
       allowMultiple: true,
     );
 

lib/services/image_manager.dart

@@ -21,7 +21,7 @@ class ImageManager extends ChangeNotifier {
   void addImages(List<String> paths) {
     final validPaths = paths.where((p) {
       final ext = p.toLowerCase().split('.').last;
-      const supported = ['png', 'jpg', 'jpeg', 'webp', 'bmp', 'gif'];
+      const supported = ['png', 'jpg', 'jpeg', 'jfif', 'jpe', 'webp', 'bmp', 'gif', 'wbmp'];
       return supported.contains(ext) && File(p).existsSync();
     }).toList();
 

lib/services/window_persistence.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'dart:io';
 import 'package:flutter/material.dart';
+import 'package:screen_retriever/screen_retriever.dart';
 
 /// Persists and restores window position and size.
 class WindowPersistence {
@@ -51,4 +52,38 @@ class WindowPersistence {
       return null;
     }
   }
+
+  /// Cascade: place new window to the right of the previous one.
+  /// Falls to the next row (row start) when it would overflow the screen,
+  /// and wraps to the top-left if the next row also overflows.
+  static Future<Offset> cascadePosition({
+    required Offset previousPosition,
+    required Size previousSize,
+  }) async {
+    try {
+      final display = await screenRetriever.getPrimaryDisplay();
+      final workLeft = display.visiblePosition?.dx ?? 0;
+      final workTop = display.visiblePosition?.dy ?? 0;
+      final workWidth = display.visibleSize?.width ?? display.size.width;
+      final workHeight = display.visibleSize?.height ?? display.size.height;
+
+      var x = previousPosition.dx + previousSize.width;
+      var y = previousPosition.dy;
+
+      if (x + previousSize.width > workLeft + workWidth) {
+        x = workLeft;
+        y = previousPosition.dy + previousSize.height;
+      }
+
+      if (y + previousSize.height > workTop + workHeight) {
+        x = workLeft;
+        y = workTop;
+      }
+
+      return Offset(x, y);
+    } catch (_) {
+      // Fallback: keep previous position if screen info is unavailable.
+      return previousPosition;
+    }
+  }
 }