chore(deploy): remove Dokploy, switch to native docker compose + Gitea Actions
- Remove Dokploy deploy jobs from GitHub CI workflow (test + build only)
- Add .gitea/workflows/ci.yml (Gitea Actions: lint, tests, docker build verify)
- Rewrite deploy.sh: set -euo pipefail, mandatory .env.<env>, --env-file,
healthcheck on /api/health with log dump on failure
- Delete Dokploy-specific docs (3 files), update references in README,
TODO.md, architecture.md, guides, dev plan
- Remove DOKPLOY_* env vars from proto/.env.local