further improved accessibility across the application and add tooltips to action buttons

lib/widget/a11y/a11y_labels.dart

@@ -16,15 +16,17 @@ abstract final class A11yLabels {
   static const draft = 'Entwurf';
   static const yourReaction = 'deine Reaktion';
 
-  // Bilder
+  // Bilder / Kontakte
   static const profilePicture = 'Profilbild';
   static const groupPicture = 'Gruppenbild';
+  static const group = 'Gruppe';
   static const roomPlan = 'Raumplan der Schule als Grafik';
 
   // Stundenplan
   static const cancelled = 'Ausfall';
   static const breakTime = 'Pause';
   static const allDay = 'Ganztägig';
+  static const today = 'heute';
 
   /// Beschreibt eine Stundenplan-Kachel für den Screenreader, z.B.
   /// „Mathe, Raum 101, 08:00–08:45, Ausfall". Zeilenumbrüche in [location]

lib/widget/details_bottom_sheet.dart

@@ -22,13 +22,18 @@ Future<void> showDetailsBottomSheet(
         padding: EdgeInsets.only(
           bottom: 16 + MediaQuery.viewInsetsOf(sheetContext).bottom,
         ),
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          crossAxisAlignment: CrossAxisAlignment.stretch,
-          children: [
-            if (header != null) ...[header, const Divider(height: 1)],
-            ...children(sheetContext),
-          ],
+        // Ohne dieses innere Material malt ListTile-Ink aufs Sheet-Material
+        // außerhalb des Scrollbereichs und stretcht beim Overscroll nicht mit.
+        child: Material(
+          type: MaterialType.transparency,
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.stretch,
+            children: [
+              if (header != null) ...[header, const Divider(height: 1)],
+              ...children(sheetContext),
+            ],
+          ),
         ),
       ),
     ),

lib/widget/downloads/download_tray.dart

@@ -154,13 +154,14 @@ class _DownloadTrayHostState extends State<DownloadTrayHost>
   /// The chip only shows when there's something the inline UI can't already
   /// convey: multiple downloads, a finished/failed one (no inline progress
   /// left), or a lone download whose originating screen the user has left.
-  bool _shouldShowChip(List<DownloadJob> jobs, int epoch) => shouldShowDownloadChip(
-    sheetOpen: _sheetOpen,
-    jobCount: jobs.length,
-    anySurfaced: jobs.any(
-      (j) => j.isDone || j.isFailed || (_originEpoch[j] ?? epoch) != epoch,
-    ),
-  );
+  bool _shouldShowChip(List<DownloadJob> jobs, int epoch) =>
+      shouldShowDownloadChip(
+        sheetOpen: _sheetOpen,
+        jobCount: jobs.length,
+        anySurfaced: jobs.any(
+          (j) => j.isDone || j.isFailed || (_originEpoch[j] ?? epoch) != epoch,
+        ),
+      );
 
   Future<void> _openSheet() async {
     if (_sheetOpen) return;
@@ -311,34 +312,48 @@ class _TrayChip extends StatelessWidget {
         label = doneCount == 1 ? 'Download fertig' : '$doneCount fertig';
       }
 
-      return Material(
-        color: colors.surfaceContainerHigh,
-        elevation: 4,
-        borderRadius: BorderRadius.circular(24),
-        shadowColor: Colors.black45,
-        child: InkWell(
-          borderRadius: BorderRadius.circular(24),
-          onTap: onTap,
-          child: Padding(
-            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
-            child: Row(
-              mainAxisSize: MainAxisSize.min,
-              children: [
-                leading,
-                const SizedBox(width: 12),
-                Flexible(
-                  child: Text(
-                    label,
-                    maxLines: 1,
-                    overflow: TextOverflow.ellipsis,
-                    style: theme.textTheme.bodyMedium?.copyWith(
-                      fontWeight: FontWeight.w600,
-                    ),
-                  ),
+      return Semantics(
+        button: true,
+        label: '$label, Downloads anzeigen',
+        onTap: onTap,
+        child: ExcludeSemantics(
+          child: Material(
+            color: colors.surfaceContainerHigh,
+            elevation: 4,
+            borderRadius: BorderRadius.circular(24),
+            shadowColor: Colors.black45,
+            child: InkWell(
+              borderRadius: BorderRadius.circular(24),
+              onTap: onTap,
+              child: Padding(
+                padding: const EdgeInsets.symmetric(
+                  horizontal: 16,
+                  vertical: 10,
                 ),
-                const SizedBox(width: 8),
-                Icon(Icons.expand_less, size: 20, color: colors.onSurfaceVariant),
-              ],
+                child: Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    leading,
+                    const SizedBox(width: 12),
+                    Flexible(
+                      child: Text(
+                        label,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: theme.textTheme.bodyMedium?.copyWith(
+                          fontWeight: FontWeight.w600,
+                        ),
+                      ),
+                    ),
+                    const SizedBox(width: 8),
+                    Icon(
+                      Icons.expand_less,
+                      size: 20,
+                      color: colors.onSurfaceVariant,
+                    ),
+                  ],
+                ),
+              ),
             ),
           ),
         ),

lib/widget/file_viewer.dart

@@ -186,6 +186,7 @@ class _FileViewerState extends State<FileViewer> {
       ...actions,
       if (showActionsMenu)
         PopupMenuButton<FileViewingActions>(
+          tooltip: 'Dateiaktionen',
           onSelected: _handleAction,
           itemBuilder: (context) => _availableActions()
               .map(
@@ -282,8 +283,10 @@ class _FileViewerState extends State<FileViewer> {
     ),
   );
 
-  Widget _buildPdfView() =>
-      Scaffold(appBar: _appbar(), body: DeferredPdfViewer(path: widget.path));
+  Widget _buildPdfView() => Scaffold(
+    appBar: _appbar(),
+    body: DeferredPdfViewer(path: widget.path),
+  );
 
   Widget _buildVideoView() => Scaffold(
     appBar: _appbar(),