fix(s3): keep host-less bucket catch-all so reverse proxies work (#9540)

When s3.domainName is set, all bucket-prefix routes were gated on a
matching Host header. Requests that arrive via an IP, an unlisted
hostname, or a reverse proxy that rewrites Host hit no router and bounce
back as 405/404 (and 503 once a proxy maps the upstream error).

Register the path-style catch-all unconditionally, after the
host-specific routers, so it only fires when no Host matcher applies.

weed/s3api/s3api_server.go

@@ -684,9 +684,12 @@ func (s3a *S3ApiServer) registerRouter(router *mux.Router) {
 			routers = append(routers, apiRouter.Host(
 				fmt.Sprintf("%s.%s", "{bucket:.+}", virtualHost)).Subrouter())
 		}
-	} else {
-		routers = append(routers, apiRouter.PathPrefix("/{bucket}").Subrouter())
 	}
+	// Always register a Host-less path-style catch-all last so requests that
+	// arrive via an IP, an unlisted hostname, or a reverse proxy that rewrites
+	// the Host header still match bucket routes. Host-specific routers above
+	// take precedence because they were registered first.
+	routers = append(routers, apiRouter.PathPrefix("/{bucket}").Subrouter())
 
 	// Get CORS middleware instance with caching
 	corsMiddleware := s3a.getCORSMiddleware()