Add search, offline queue, app icon, and UI polish

- Collapsible search in notes and tasks: magnifying glass in AppBar
  expands to a text field inline; close button resets the filter
- Offline capture queue: failed quick-captures (NetworkException) are
  persisted to SharedPreferences and retried automatically on next
  successful submit or app start; badge shows pending count
- App icon: book-with-sparkle logo from FabledAssistant SVG rendered
  at all Android densities with adaptive icon (indigo #6366f1 bg)
- Dark mode subtitle fix: use colorScheme.onSurfaceVariant for note
  preview and conversation timestamp text
- Remove swipe-to-delete (accidental deletions); long-press remains
- Chat: SSE streaming reliability, polling fallback, title patching
- Settings: theme toggle (system/light/dark) persisted to prefs
- Notes: delete button in edit screen; body preview in list
- Tasks: fix delete dialog context; description search support

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/screens/notes/note_edit_screen.dart

@@ -41,6 +41,30 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
     _loaded = true;
   }
 
+  Future<void> _delete() async {
+    final confirm = await showDialog<bool>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Delete note?'),
+        content: Text(_titleController.text),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(dialogContext, false),
+            child: const Text('Cancel'),
+          ),
+          TextButton(
+            onPressed: () => Navigator.pop(dialogContext, true),
+            child: const Text('Delete'),
+          ),
+        ],
+      ),
+    );
+    if (confirm == true) {
+      await ref.read(notesProvider.notifier).delete(widget.noteId!);
+      if (mounted) context.pop();
+    }
+  }
+
   Future<void> _save() async {
     final title = _titleController.text.trim();
     final body = _contentController.text;
@@ -79,6 +103,12 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
           appBar: AppBar(
             title: Text(widget.noteId == null ? 'New Note' : 'Edit Note'),
             actions: [
+              if (widget.noteId != null)
+                IconButton(
+                  icon: const Icon(Icons.delete_outline),
+                  tooltip: 'Delete',
+                  onPressed: _delete,
+                ),
               IconButton(
                 icon: Icon(_preview ? Icons.edit : Icons.preview),
                 tooltip: _preview ? 'Edit' : 'Preview',