feat(ops): add object storage management and site-mapping CSV import/export

Ship the Ops backstage 对象存储 page (browse / upload / move / delete /
folder ops) backed by a new object-storage service + handler, with the
shared storage client extended with List/Stat/Copy/Usage/DownloadURL so
both MinIO and Aliyun providers cover the new surface. Add
ForcePathStyle to the object-storage config and treat r2/s3/custom_s3
as external providers so Cloudflare R2 and other S3-compatibles can
share the MinIO client path without spinning up the bundled MinIO.

Also add CSV import/export + template download to the site-domain
mappings page, raise gin MaxMultipartMemory to 8 MiB for the new
multipart endpoints, register Ops swagger routes, and extend the
descriptions-parity test to cover the ops router.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/shared/config/config_test.go

@@ -112,12 +112,14 @@ func TestLoadAppliesObjectStorageEnvOverrides(t *testing.T) {
 	t.Setenv("OBJECT_STORAGE_BUCKET_ACL", "private")
 	t.Setenv("OBJECT_STORAGE_OBJECT_ACL", "public-read")
 	t.Setenv("OBJECT_STORAGE_SIGNED_URL_TTL", "45m")
+	t.Setenv("OBJECT_STORAGE_FORCE_PATH_STYLE", "true")
 
 	configPath := writeTestConfig(t, `
 object_storage:
   bucket_acl: public-read
   object_acl: private
   signed_url_ttl: 10m
+  force_path_style: false
 `)
 
 	cfg, err := Load(configPath)
@@ -134,6 +136,9 @@ object_storage:
 	if cfg.ObjectStorage.SignedURLTTL != 45*time.Minute {
 		t.Fatalf("expected env signed url ttl, got %s", cfg.ObjectStorage.SignedURLTTL)
 	}
+	if !cfg.ObjectStorage.ForcePathStyle {
+		t.Fatal("expected env force path style true")
+	}
 }
 
 func TestLoadAppliesBrandLibraryDefaults(t *testing.T) {