style: doppelte Unterstriche in Closure-Parametern bereinigen

Dart 3 erlaubt mehrere Wildcard-Parameter mit demselben Namen "_" in
einem Scope, daher sind __ / ___ für ungenutzte Callback-Parameter
(pageBuilder, errorBuilder etc.) unnötig. Rein mechanische Änderung,
keine Verhaltensänderung.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/widgets/mxc_image.dart

@@ -90,7 +90,7 @@ class _MxcAvatarState extends State<MxcAvatar> {
               width: widget.size,
               height: widget.size,
               fit: BoxFit.cover,
-              errorBuilder: (_, __, ___) => widget.placeholder(context),
+              errorBuilder: (_, _, _) => widget.placeholder(context),
             ),
           );
         }
@@ -194,7 +194,7 @@ class _MxcImageState extends State<MxcImage> {
             width: widget.width,
             height: widget.height,
             gaplessPlayback: true,
-            errorBuilder: (_, __, ___) =>
+            errorBuilder: (_, _, _) =>
                 widget.placeholder ?? const SizedBox.shrink(),
           );
         }

lib/widgets/pyramid_loader.dart

@@ -60,7 +60,7 @@ class _PyramidLoaderState extends State<PyramidLoader>
 
     final painter = AnimatedBuilder(
       animation: _ctrl,
-      builder: (_, __) => CustomPaint(
+      builder: (_, _) => CustomPaint(
         painter: _PyramidPainter(
           yaw: _yawAt(_ctrl.value),
           accent: accent,
@@ -82,7 +82,7 @@ class _PyramidLoaderState extends State<PyramidLoader>
               fit: BoxFit.contain,
               repeat: true,
               animate: true,
-              errorBuilder: (_, __, ___) => painter,
+              errorBuilder: (_, _, _) => painter,
             ),
           ),
         ),

lib/widgets/search_modal.dart

@@ -723,7 +723,7 @@ class _SearchThumbState extends State<_SearchThumb> {
         height: size,
         child: _bytes != null
             ? Image.memory(_bytes!, fit: BoxFit.cover,
-                errorBuilder: (_, __, ___) => _placeholder(pt))
+                errorBuilder: (_, _, _) => _placeholder(pt))
             : _placeholder(pt),
       ),
     );

lib/widgets/settings_modal.dart

@@ -1306,7 +1306,7 @@ class _ProfileSectionState extends ConsumerState<_ProfileSection> {
                       children: [
                         if (_pendingServerBanner != null)
                           Image.memory(_pendingServerBanner!, fit: BoxFit.cover,
-                              errorBuilder: (_, __, ___) => const SizedBox.shrink())
+                              errorBuilder: (_, _, _) => const SizedBox.shrink())
                         else if (existingMxc != null && client != null)
                           MxcImage(mxcUri: existingMxc, client: client, fit: BoxFit.cover)
                         else

lib/widgets/share_target_dialog.dart

@@ -27,8 +27,8 @@ class ShareTargetDialog {
       barrierLabel: 'Teilen',
       barrierColor: Colors.black54,
       transitionDuration: const Duration(milliseconds: 180),
-      pageBuilder: (_, __, ___) => _ShareTargetPicker(client: client, share: share),
-      transitionBuilder: (_, anim, __, child) {
+      pageBuilder: (_, _, _) => _ShareTargetPicker(client: client, share: share),
+      transitionBuilder: (_, anim, _, child) {
         final curved = CurvedAnimation(parent: anim, curve: Curves.easeOutBack);
         return FadeTransition(
           opacity: anim,