Initial commit: habit tracker PWA with Google OAuth, push notifications

FastAPI + SQLAlchemy/Alembic + MariaDB backend with Jinja2/htmx/Alpine
server-rendered frontend. Multi-user via Google OAuth, daily habit
tracking, monthly/weekly history views, Web Push reminders via
APScheduler, and PWA support (manifest, service worker, offline caching).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/models/__init__.py

@@ -0,0 +1,16 @@
+from app.models.habit import Habit, HabitStatus, HabitType
+from app.models.habit_log import HabitLog
+from app.models.notification_log import HabitNotificationLog, SummaryNotificationLog
+from app.models.push_subscription import PushSubscription
+from app.models.user import User
+
+__all__ = [
+    "Habit",
+    "HabitStatus",
+    "HabitType",
+    "HabitLog",
+    "HabitNotificationLog",
+    "SummaryNotificationLog",
+    "PushSubscription",
+    "User",
+]