feat: implement Iteration 6 — profile screen

Add ProfileService (GET/PUT /profile), ProfileNotifier provider,
and full ProfileScreen with body-params, goal/activity, daily-calories
sections and logout confirmation. EditProfileSheet lets user update
name, height, weight, age, gender, goal and activity; backend
auto-recalculates daily_calories via Mifflin-St Jeor.
HomeScreen greeting now shows the user's real name from profileProvider.

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

client/lib/features/profile/profile_provider.dart

@@ -0,0 +1,32 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../shared/models/user.dart';
+import 'profile_service.dart';
+
+class ProfileNotifier extends StateNotifier<AsyncValue<User>> {
+  final ProfileService _service;
+
+  ProfileNotifier(this._service) : super(const AsyncValue.loading()) {
+    load();
+  }
+
+  Future<void> load() async {
+    state = const AsyncValue.loading();
+    state = await AsyncValue.guard(() => _service.getProfile());
+  }
+
+  Future<bool> update(UpdateProfileRequest req) async {
+    try {
+      final updated = await _service.updateProfile(req);
+      state = AsyncValue.data(updated);
+      return true;
+    } catch (_) {
+      return false;
+    }
+  }
+}
+
+final profileProvider =
+    StateNotifierProvider<ProfileNotifier, AsyncValue<User>>(
+  (ref) => ProfileNotifier(ref.read(profileServiceProvider)),
+);