prepare app for public app store distribution

- rebrand from 습관 트래커 to 해빗랩 across templates, manifest, service worker
- add HTTPS redirect middleware for reverse-proxied deployments
- add public landing page (/) and privacy policy page with real data
  handling disclosures
- add in-app account deletion (Apple review requirement)
- add Android TWA Digital Asset Links support (/.well-known/assetlinks.json)
- add SFTP deployment script for the Synology-hosted server

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

app/services/user_service.py

@@ -0,0 +1,14 @@
+from sqlalchemy.orm import Session
+
+from app.models.user import User
+
+
+def delete_account(db: Session, user: User) -> None:
+    """계정과 그에 딸린 모든 데이터를 삭제한다.
+
+    Habit/PushSubscription/HabitLog/HabitNotificationLog/SummaryNotificationLog는 전부
+    user.id 기준 DB 레벨 ON DELETE CASCADE로 연결돼 있어(마이그레이션 0004/0005 참고),
+    User 행만 지우면 나머지는 MariaDB가 알아서 정리한다.
+    """
+    db.delete(user)
+    db.commit()