Add Projects feature; sync Note/Task models with backend additions

## New: Projects
- Project model, API, repository, Riverpod provider
- ProjectListScreen: active/archived sections, create dialog, long-press status/delete
- ProjectSelector widget: DropdownButtonFormField for note + task editors
- Projects tab added to shell (bottom nav + navigation rail, 4th position)
- /projects route registered in GoRouter ShellRoute

## Updated: Note model
- Added tags: List<String>, projectId: int?, milestoneId: int?
- NotesApi.create/update pass tags and project_id
- NotesRepository and NotesNotifier signatures updated
- NoteEditScreen: chip-based tag input + ProjectSelector

## Updated: Task model
- Added projectId: int?, milestoneId: int?, parentId: int?
- TasksApi.create passes project_id; update payload includes project_id
- TasksRepository and TasksNotifier signatures updated
- TaskEditScreen: ProjectSelector added; project_id sent on save

## Provider fix
- ProjectsNotifier.update renamed to updateProject to avoid conflict
  with AsyncNotifier.update(FutureOr<State> Function(State)) base method

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

lib/screens/notes/note_edit_screen.dart

@@ -7,6 +7,7 @@ import '../../core/exceptions.dart';
 import '../../core/wikilink_syntax.dart';
 import '../../providers/api_client_provider.dart';
 import '../../providers/notes_provider.dart';
+import '../../widgets/project_selector.dart';
 
 class NoteEditScreen extends ConsumerStatefulWidget {
   final int? noteId;
@@ -19,10 +20,12 @@ class NoteEditScreen extends ConsumerStatefulWidget {
 class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
   final _titleController = TextEditingController();
   final _contentController = TextEditingController();
+  final _tagController = TextEditingController();
+  List<String> _tags = [];
+  int? _projectId;
   bool _preview = false;
   bool _saving = false;
 
-  // Future is created once in initState so FutureBuilder never restarts it.
   late final Future<void> _initFuture;
 
   @override
@@ -36,6 +39,7 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
   void dispose() {
     _titleController.dispose();
     _contentController.dispose();
+    _tagController.dispose();
     super.dispose();
   }
 
@@ -44,6 +48,24 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
         await ref.read(notesRepositoryProvider).getOne(widget.noteId!);
     _titleController.text = note.title;
     _contentController.text = note.body;
+    _tags = List<String>.from(note.tags);
+    _projectId = note.projectId;
+  }
+
+  void _addTag(String raw) {
+    final tag = raw.trim().replaceAll(',', '').toLowerCase();
+    if (tag.isEmpty || _tags.contains(tag)) {
+      _tagController.clear();
+      return;
+    }
+    setState(() {
+      _tags = [..._tags, tag];
+      _tagController.clear();
+    });
+  }
+
+  void _removeTag(String tag) {
+    setState(() => _tags = _tags.where((t) => t != tag).toList());
   }
 
   Future<void> _delete() async {
@@ -81,12 +103,22 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
     setState(() => _saving = true);
     try {
       if (widget.noteId == null) {
-        await ref.read(notesProvider.notifier).create(title, body);
+        await ref.read(notesProvider.notifier).create(
+              title,
+              body,
+              tags: _tags,
+              projectId: _projectId,
+            );
         if (mounted) context.pop();
       } else {
-        await ref
-            .read(notesProvider.notifier)
-            .updateNote(widget.noteId!, title, body);
+        await ref.read(notesProvider.notifier).updateNote(
+              widget.noteId!,
+              title,
+              body,
+              tags: _tags,
+              projectId: _projectId,
+              clearProject: _projectId == null,
+            );
         if (mounted) context.pop();
       }
     } on AppException catch (e) {
@@ -147,7 +179,23 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
                         textInputAction: TextInputAction.next,
                       ),
                     ),
-                    const Divider(),
+                    Padding(
+                      padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
+                      child: _TagInput(
+                        tags: _tags,
+                        controller: _tagController,
+                        onAdd: _addTag,
+                        onRemove: _removeTag,
+                      ),
+                    ),
+                    Padding(
+                      padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
+                      child: ProjectSelector(
+                        value: _projectId,
+                        onChanged: (id) => setState(() => _projectId = id),
+                      ),
+                    ),
+                    const Divider(height: 1),
                     Expanded(
                       child: _preview
                           ? Markdown(
@@ -177,3 +225,57 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
     );
   }
 }
+
+class _TagInput extends StatelessWidget {
+  final List<String> tags;
+  final TextEditingController controller;
+  final ValueChanged<String> onAdd;
+  final ValueChanged<String> onRemove;
+
+  const _TagInput({
+    required this.tags,
+    required this.controller,
+    required this.onAdd,
+    required this.onRemove,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Wrap(
+      spacing: 6,
+      runSpacing: 4,
+      crossAxisAlignment: WrapCrossAlignment.center,
+      children: [
+        ...tags.map(
+          (tag) => Chip(
+            label: Text('#$tag', style: const TextStyle(fontSize: 12)),
+            materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
+            padding: const EdgeInsets.symmetric(horizontal: 4),
+            deleteIcon: const Icon(Icons.close, size: 14),
+            onDeleted: () => onRemove(tag),
+          ),
+        ),
+        SizedBox(
+          width: 120,
+          child: TextField(
+            controller: controller,
+            decoration: const InputDecoration(
+              hintText: 'Add tag…',
+              border: InputBorder.none,
+              isDense: true,
+              contentPadding: EdgeInsets.symmetric(vertical: 4),
+            ),
+            style: const TextStyle(fontSize: 13),
+            textInputAction: TextInputAction.done,
+            onSubmitted: onAdd,
+            onChanged: (v) {
+              if (v.endsWith(',') || v.endsWith(' ')) {
+                onAdd(v.replaceAll(RegExp(r'[, ]+$'), ''));
+              }
+            },
+          ),
+        ),
+      ],
+    );
+  }
+}