Add Garmin Connect auto-sync via python-garminconnect

- GarminConnectConfig model stores encrypted credentials and OAuth token
- garmin_connect_sync service: token-based auth with password fallback,
  activity FIT download + queue, daily wellness from JSON API
- Celery beat schedule: sync_all_garmin_connect fires every hour
- New API router /api/garmin-sync: config CRUD, manual trigger
- Beat container added to docker-compose.yml and docker-compose.deploy.yml
- ProfilePage: Garmin Connect section with connect/update/disconnect and Sync now

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

backend/app/main.py

@@ -6,7 +6,7 @@ import asyncio
 
 from app.core.database import engine, AsyncSessionLocal, Base
 from app.core.config import settings
-from app.api import auth, activities, routes, health, records, upload, profile
+from app.api import auth, activities, routes, health, records, upload, profile, garmin_sync
 
 
 async def init_db():
@@ -98,6 +98,7 @@ app.include_router(health.router, prefix="/api/health-metrics", tags=["health"])
 app.include_router(records.router, prefix="/api/records", tags=["records"])
 app.include_router(upload.router, prefix="/api/upload", tags=["upload"])
 app.include_router(profile.router, prefix="/api/profile", tags=["profile"])
+app.include_router(garmin_sync.router, prefix="/api/garmin-sync", tags=["garmin-sync"])
 
 
 @app.get("/health")