feat(docker): add Docker Hub authentication for CI/CD workflows

- Introduced `docker_hub_token` and `docker_hub_username` secrets for Docker Hub login in CI/CD workflows.
- Updated `.gitea/workflows/ci.yaml`, `.gitea/workflows/cd.yaml`, and `.gitea/workflows/quality.yaml` to utilize these secrets for Docker Hub authentication.
- Enhanced README and releasing documentation to clarify the use of Docker Hub credentials for image mirroring and builds.

docs/releasing.md

@@ -44,13 +44,13 @@ Workflows: [.gitea/workflows/ci.yaml](../.gitea/workflows/ci.yaml), [.gitea/work
 
 ## Секреты Gitea
 
-Один PAT — **`ACTIONS_PAT`** (Settings → Actions → Secrets).
+PAT репозитория — **`ACTIONS_PAT`** (Settings → Actions → Secrets).
 
-| Право PAT | Зачем |
-|-----------|--------|
-| push tags | git tag `vX.Y.Z` на commit merge |
-| releases | Gitea Release + notes |
-| packages (Container Registry) | push образов |
+| Секрет | Зачем |
+|--------|--------|
+| `ACTIONS_PAT` | git tag `vX.Y.Z`, Gitea Release, push в Container Registry |
+| `docker_hub_token` | логин на Docker Hub при зеркале base-образов и bake (лимиты anonymous pull) |
+| `docker_hub_username` | имя пользователя Docker Hub; если пусто — `gitea.actor` |
 
 Fallback для **git tag**: `github.token`, если PAT недоступен. Push образов в Container Registry — **только `ACTIONS_PAT`** (у job token Gitea нет права packages).