Add supplements, kettlebell, calendar, push notifications, and PWA support

- Supplement tracking: CRUD endpoints, /today, /logs, Supplements page
- Kettlebell workouts: session tracking, analytics endpoint, ActiveSession page
- Calendar module: events CRUD, calendar components
- Push notifications: VAPID keys, PushSubscription model, APScheduler reminders,
  service worker with push/notificationclick handlers, Profile notifications UI
- PWA: vite-plugin-pwa, manifest, icons, service worker generation
- Frontend: TypeScript types, API modules, ConfirmModal, toast notifications
- Auth fixes: password hashing, nutrition endpoint auth
- CLAUDE.md: project documentation and development guide

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/push_subscription.py

@@ -0,0 +1,17 @@
+from datetime import datetime
+from typing import Optional
+
+from sqlmodel import Field, SQLModel
+
+
+class PushSubscription(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id", index=True)
+    endpoint: str = Field(unique=True, index=True)
+    p256dh: str
+    auth: str
+    reminder_hour: int = Field(default=9)
+    reminder_minute: int = Field(default=0)
+    timezone: str = Field(default="UTC")
+    is_active: bool = Field(default=True)
+    created_at: datetime = Field(default_factory=datetime.utcnow)