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/providers/api_client_provider.dart

@@ -6,11 +6,13 @@ import '../data/api/api_client.dart';
 import '../data/api/auth_api.dart';
 import '../data/api/chat_api.dart';
 import '../data/api/notes_api.dart';
+import '../data/api/projects_api.dart';
 import '../data/api/quick_capture_api.dart';
 import '../data/api/tasks_api.dart';
 import '../data/repositories/auth_repository.dart';
 import '../data/repositories/chat_repository.dart';
 import '../data/repositories/notes_repository.dart';
+import '../data/repositories/projects_repository.dart';
 import '../data/repositories/tasks_repository.dart';
 import 'settings_provider.dart';
 
@@ -45,6 +47,10 @@ final quickCaptureApiProvider = Provider<QuickCaptureApi>((ref) {
   return QuickCaptureApi(ref.watch(dioProvider));
 });
 
+final projectsApiProvider = Provider<ProjectsApi>((ref) {
+  return ProjectsApi(ref.watch(dioProvider));
+});
+
 final authRepositoryProvider = Provider<AuthRepository>((ref) {
   return AuthRepository(ref.watch(authApiProvider));
 });
@@ -60,3 +66,7 @@ final tasksRepositoryProvider = Provider<TasksRepository>((ref) {
 final chatRepositoryProvider = Provider<ChatRepository>((ref) {
   return ChatRepository(ref.watch(chatApiProvider));
 });
+
+final projectsRepositoryProvider = Provider<ProjectsRepository>((ref) {
+  return ProjectsRepository(ref.watch(projectsApiProvider));
+});

lib/providers/notes_provider.dart

@@ -12,16 +12,35 @@ class NotesNotifier extends AsyncNotifier<List<Note>> {
     return ref.watch(notesRepositoryProvider).getAll();
   }
 
-  Future<Note> create(String title, String body) async {
-    final note =
-        await ref.read(notesRepositoryProvider).create(title, body);
+  Future<Note> create(
+    String title,
+    String body, {
+    List<String> tags = const [],
+    int? projectId,
+  }) async {
+    final note = await ref
+        .read(notesRepositoryProvider)
+        .create(title, body, tags: tags, projectId: projectId);
     state = AsyncData([...state.valueOrNull ?? [], note]);
     return note;
   }
 
-  Future<Note> updateNote(int id, String title, String body) async {
-    final updated =
-        await ref.read(notesRepositoryProvider).update(id, title, body);
+  Future<Note> updateNote(
+    int id,
+    String title,
+    String body, {
+    List<String> tags = const [],
+    int? projectId,
+    bool clearProject = false,
+  }) async {
+    final updated = await ref.read(notesRepositoryProvider).update(
+          id,
+          title,
+          body,
+          tags: tags,
+          projectId: projectId,
+          clearProject: clearProject,
+        );
     state = AsyncData([
       for (final n in state.valueOrNull ?? [])
         if (n.id == id) updated else n,

lib/providers/projects_provider.dart

@@ -0,0 +1,49 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../data/models/project.dart';
+import 'api_client_provider.dart';
+
+final projectsProvider =
+    AsyncNotifierProvider<ProjectsNotifier, List<Project>>(
+        ProjectsNotifier.new);
+
+class ProjectsNotifier extends AsyncNotifier<List<Project>> {
+  @override
+  Future<List<Project>> build() async {
+    return ref.watch(projectsRepositoryProvider).getAll();
+  }
+
+  Future<Project> create({
+    required String title,
+    String? description,
+    String? goal,
+    String? color,
+  }) async {
+    final project = await ref.read(projectsRepositoryProvider).create(
+          title: title,
+          description: description,
+          goal: goal,
+          color: color,
+        );
+    state = AsyncData([...state.valueOrNull ?? [], project]);
+    return project;
+  }
+
+  Future<Project> updateProject(int id, Map<String, dynamic> fields) async {
+    final updated =
+        await ref.read(projectsRepositoryProvider).update(id, fields);
+    state = AsyncData([
+      for (final p in state.valueOrNull ?? [])
+        if (p.id == id) updated else p,
+    ]);
+    return updated;
+  }
+
+  Future<void> delete(int id) async {
+    await ref.read(projectsRepositoryProvider).delete(id);
+    state = AsyncData([
+      for (final p in state.valueOrNull ?? [])
+        if (p.id != id) p,
+    ]);
+  }
+}

lib/providers/tasks_provider.dart

@@ -18,6 +18,7 @@ class TasksNotifier extends AsyncNotifier<List<Task>> {
     required TaskStatus status,
     required TaskPriority priority,
     DateTime? dueDate,
+    int? projectId,
   }) async {
     final task = await ref.read(tasksRepositoryProvider).create(
           title: title,
@@ -25,6 +26,7 @@ class TasksNotifier extends AsyncNotifier<List<Task>> {
           status: status,
           priority: priority,
           dueDate: dueDate,
+          projectId: projectId,
         );
     state = AsyncData([...state.valueOrNull ?? [], task]);
     return task;