RegWatch backend : FastAPI + Postgres partagé + Docker/CI homelab

- SECRET_KEY et DATABASE_URL externalisés (Vault -> env), plus de secret en dur
- SQLite -> postgres-shared (psycopg2), schéma créé au boot (entrypoint.sh)
- Dockerfile + docker-compose (Watchtower) + .gitea/workflows/build.yml

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -0,0 +1,11 @@
+fastapi
+uvicorn
+sqlalchemy
+requests
+beautifulsoup4
+pydantic
+ollama
+python-jose[cryptography]
+passlib[argon2]
+python-multipart
+psycopg2-binary