feat: configurable body limit + Docker delete API

- Add body_limit_mb to ServerConfig (default 2048MB, env NORA_BODY_LIMIT_MB)
- Replace hardcoded 100MB DefaultBodyLimit with config value
- Add DELETE /v2/{name}/manifests/{reference} endpoint (Docker Registry V2 spec)
- Add DELETE /v2/{name}/blobs/{digest} endpoint
- Add namespace-qualified variants for both DELETE endpoints
- Return 202 Accepted on success, 404 with MANIFEST_UNKNOWN/BLOB_UNKNOWN errors
- Audit log integration for delete operations

Fixes: 413 Payload Too Large on Docker push >100MB

nora-registry/src/main.rs

@@ -347,7 +347,9 @@ async fn run_server(config: Config, storage: Storage) {
     let app = Router::new()
         .merge(public_routes)
         .merge(app_routes)
-        .layer(DefaultBodyLimit::max(100 * 1024 * 1024)) // 100MB default body limit
+        .layer(DefaultBodyLimit::max(
+            state.config.server.body_limit_mb * 1024 * 1024,
+        ))
         .layer(middleware::from_fn(request_id::request_id_middleware))
         .layer(middleware::from_fn(metrics::metrics_middleware))
         .layer(middleware::from_fn_with_state(
@@ -366,6 +368,7 @@ async fn run_server(config: Config, storage: Storage) {
         version = env!("CARGO_PKG_VERSION"),
         storage = state.storage.backend_name(),
         auth_enabled = state.auth.is_some(),
+        body_limit_mb = state.config.server.body_limit_mb,
         "Nora started"
     );