Add CI/CD pipeline with Gitea Actions and production deployment

- Production Dockerfiles: backend (gunicorn + uvicorn workers),
  frontend (multi-stage Node build + nginx with API proxy)
- docker-compose.prod.yml: integrates with VPS nginx-proxy via
  VIRTUAL_HOST for auto-TLS at fit.cescalante.dev
- GitHub Actions workflow (Gitea Actions-compatible): builds images
  and deploys on push to main via self-hosted runner
- Make CORS origins configurable via CORS_ORIGINS env var

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

backend/app/config.py

@@ -6,6 +6,12 @@ class Settings(BaseSettings):
     OPENAI_API_KEY: str | None = None
     SECRET_KEY: str = "changethis"
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 8  # 8 days
+    CORS_ORIGINS: str = "http://localhost:5173,http://localhost:5174,http://localhost:3000"
+    VAPID_PRIVATE_KEY: str = ""
+    VAPID_PUBLIC_KEY: str = ""
+    VAPID_MAILTO: str = "mailto:admin@example.com"
+    PUSH_REMINDER_HOUR: int = 9
+    PUSH_REMINDER_MINUTE: int = 0
 
     class Config:
         env_file = ".env"