feat(deploy): CI/CD Gitea Actions + stack Docker prod pour xip.kerboul.me

- docker-compose.prod.yml: postgres + redis + backend (bun) + web (nginx single-origin)
- backend/Dockerfile + entrypoint: prisma migrate deploy + seed idempotent au boot
- frontend/Dockerfile: build Vite (VITE_API_URL=https://xip.kerboul.me) servi par nginx
- deploy/nginx.conf: proxy /api + /ws vers le backend, SPA fallback
- .gitea/workflows/deploy.yml: auto-deploy SSH sur push main (runner CT121 -> CT502)
- scripts/deploy.sh: pull + rebuild de la stack
- mode open-bar (XIP_OPEN_BAR): paywall off pour tous en prod, via isFree() centralise

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

.gitignore

@@ -2,6 +2,7 @@ node_modules/
 dist/
 .env
 .env.local
+.env.prod
 *.log
 .DS_Store
 Thumbs.db