feat: add Docker image metadata support

- Store metadata (.meta.json) alongside manifests with:
  - push_timestamp, last_pulled, downloads counter
  - size_bytes, os, arch, variant
  - layers list with digest and size
- Update metadata on manifest pull (increment downloads, update last_pulled)
- Extract OS/arch from config blob on push
- Extend UI API TagInfo with metadata fields
- Add public_url config option for pull commands
- Add Docker upstream proxy with auth support
- Add raw repository support
- Bump version to 0.2.12

nora-registry/src/ui/mod.rs

@@ -108,7 +108,7 @@ async fn docker_detail(
         &Query(query),
         headers.get("cookie").and_then(|v| v.to_str().ok()),
     );
-    let detail = get_docker_detail(&state.storage, &name).await;
+    let detail = get_docker_detail(&state, &name).await;
     Html(render_docker_detail(&name, &detail, lang))
 }