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.

.gitea/README.md

@@ -39,6 +39,8 @@ Runner: `ubuntu-latest`, **bird2** из apt, Docker для **docker-check** (PR)
 
 **`ACTIONS_PAT`**: push tags, releases, Container Registry. Для git tag fallback: `github.token`. Push OCI — **только PAT** (у `GITEA_TOKEN` нет права packages).
 
+**`docker_hub_token`**: PAT Docker Hub (Settings → Actions → Secrets, можно на уровне организации). Логин перед зеркалом `docker.io` и `bake`, чтобы не ловить anonymous 429. Логин: `docker_hub_username` (если задан) или `gitea.actor`.
+
 ### Теги образов
 
 ```text