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>

check_db.py

@@ -0,0 +1,11 @@
+from database.database import SessionLocal
+from database.models import Document
+
+db = SessionLocal()
+
+documents = db.query(Document).all()
+
+print(f"Total documents: {len(documents)}")
+
+for doc in documents[:5]:
+    print(doc.title)