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>
