feat(T6/T7): supervizare worker (healthcheck+autoheal) + backup online + cheie partajata

T6 — worker supravegheat:
- app/worker/healthcheck.py: probe pe heartbeat-ul din DB (beat invechit -> exit 1).
  Prinde worker-ul agatat (proces viu, beat inghetat) pe care restart:always nu-l
  vede. Cablat ca healthcheck pe serviciul worker in compose.
- sidecar autoheal: restarteaza efectiv containerul unhealthy (compose simplu doar
  marcheaza, nu restarteaza la unhealthy).

T7 — deploy:
- tools/backup.py: backup ONLINE via Connection.backup (WAL nu se copiaza sigur cu
  cp); --keep N roteste snapshot-urile.
- .env.example documenteaza env-urile; volum persistent numit deja in compose.

Fix critic (split api/worker in 2 containere): AUTOPASS_CREDS_KEY trebuie PARTAJATA
api<->worker, altfel worker nu decripteaza creds-urile criptate de API -> submission
blocate. Acum impusa in compose (${...:?} -> fail explicit daca lipseste).
.gitignore: exceptie !.env.example.

5 teste noi (tests/test_deploy.py). 100 pass total.

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

.gitignore

@@ -13,6 +13,7 @@ settings.xml
 *.key
 .env
 .env.*
+!.env.example
 
 # --- VFP: programe compilate (se regenerează din .prg) ---
 *.fxp