fixed several runtime errors from client error reports

lib/widget/avatar_actions_sheet.dart

@@ -42,7 +42,7 @@ Future<AvatarSheetResult?> showAvatarActionsSheet(
         onTap: () async {
           final bytes = await _pickAndCrop(
             sheetContext,
-            () => FilePick.singleGalleryPick(sheetContext),
+            () => FilePick.singleGalleryPick(sheetContext, forCrop: true),
           );
           if (bytes == null || !sheetContext.mounted) return;
           result = AvatarUploadResult(bytes);
@@ -55,7 +55,7 @@ Future<AvatarSheetResult?> showAvatarActionsSheet(
         onTap: () async {
           final bytes = await _pickAndCrop(
             sheetContext,
-            () => FilePick.cameraPick(sheetContext),
+            () => FilePick.cameraPick(sheetContext, forCrop: true),
           );
           if (bytes == null || !sheetContext.mounted) return;
           result = AvatarUploadResult(bytes);

lib/widget/chat_background_picker_sheet.dart

@@ -22,7 +22,7 @@ Future<Uint8List?> showChatBackgroundPickerSheet(BuildContext context) async {
         title: const Text('Aus Galerie wählen'),
         onTap: () async {
           final bytes = await _pickRaw(
-            () => FilePick.singleGalleryPick(sheetContext),
+            () => FilePick.singleGalleryPick(sheetContext, forCrop: true),
           );
           if (bytes == null || !sheetContext.mounted) return;
           result = bytes;
@@ -33,7 +33,9 @@ Future<Uint8List?> showChatBackgroundPickerSheet(BuildContext context) async {
         leading: const Icon(Icons.photo_camera_outlined),
         title: const Text('Foto aufnehmen'),
         onTap: () async {
-          final bytes = await _pickRaw(() => FilePick.cameraPick(sheetContext));
+          final bytes = await _pickRaw(
+            () => FilePick.cameraPick(sheetContext, forCrop: true),
+          );
           if (bytes == null || !sheetContext.mounted) return;
           result = bytes;
           Navigator.of(sheetContext).pop();

lib/widget/file_pick.dart

@@ -23,11 +23,31 @@ class FilePick {
         return pickedImages.isNotEmpty ? pickedImages : null;
       });
 
-  static Future<XFile?> singleGalleryPick(BuildContext context) =>
-      _guarded(context, () => _picker.pickImage(source: ImageSource.gallery));
+  static Future<XFile?> singleGalleryPick(
+    BuildContext context, {
+    bool forCrop = false,
+  }) => _pickImage(context, ImageSource.gallery, forCrop: forCrop);
 
-  static Future<XFile?> cameraPick(BuildContext context) =>
-      _guarded(context, () => _picker.pickImage(source: ImageSource.camera));
+  static Future<XFile?> cameraPick(
+    BuildContext context, {
+    bool forCrop = false,
+  }) => _pickImage(context, ImageSource.camera, forCrop: forCrop);
+
+  /// [forCrop] makes the picker re-encode to a bounded JPEG: the Dart cropper
+  /// can't decode HEIC (iOS gallery default) and is slow on full-size photos.
+  static Future<XFile?> _pickImage(
+    BuildContext context,
+    ImageSource source, {
+    required bool forCrop,
+  }) => _guarded(
+    context,
+    () => _picker.pickImage(
+      source: source,
+      maxWidth: forCrop ? 2048 : null,
+      maxHeight: forCrop ? 2048 : null,
+      imageQuality: forCrop ? 90 : null,
+    ),
+  );
 
   static Future<List<String>?> documentPick() async {
     final result = await FilePicker.pickFiles(allowMultiple: true);