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/models/user.py

@@ -37,6 +37,26 @@ class User(Base):
     health_metrics = relationship("HealthMetric", back_populates="user", cascade="all, delete-orphan")
     named_routes = relationship("NamedRoute", back_populates="user", cascade="all, delete-orphan")
     weight_logs = relationship("WeightLog", back_populates="user", cascade="all, delete-orphan")
+    garmin_connect_config = relationship("GarminConnectConfig", back_populates="user", uselist=False, cascade="all, delete-orphan")
+
+
+class GarminConnectConfig(Base):
+    """Per-user Garmin Connect credentials and sync state."""
+    __tablename__ = "garmin_connect_configs"
+
+    id = Column(Integer, primary_key=True)
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, unique=True, index=True)
+    email = Column(String(256), nullable=False)
+    password_enc = Column(String(512), nullable=False)   # Fernet-encrypted
+    token_store = Column(Text, nullable=True)             # garth OAuth2 token JSON
+    sync_enabled = Column(Boolean, default=True)
+    sync_activities = Column(Boolean, default=True)
+    sync_wellness = Column(Boolean, default=True)
+    last_sync_at = Column(DateTime(timezone=True), nullable=True)
+    last_sync_status = Column(String(512), nullable=True)
+    created_at = Column(DateTime(timezone=True), default=now_utc)
+
+    user = relationship("User", back_populates="garmin_connect_config")
 
 
 class WeightLog(Base):