refactor(util): move response helper to common/response and session logic to oauth

- Relocated generic HTTP response helpers (Response, OK, Err, etc.) from internal/util/ to a dedicated internal/common/response/ package.
- Renamed ResponseAny to Any to resolve revive stuttering warnings.
- Moved session building options and cookie headers logic from internal/util/ to internal/apps/oauth/.
- Removed all direct imports of Gin/Sessions/HTTP frameworks from internal/util/ to keep general utilities 100% pure.
- Regenerated Swagger API documentation via make swagger.
- All tests and make code-check compile and pass with 0 issues.

internal/common/response/response.go

@@ -0,0 +1,34 @@
+// Copyright 2025 linux.do
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package response provides shared HTTP API response structures.
+package response
+
+// Response 通用响应体
+type Response[T any] struct {
+	ErrorMsg string `json:"error_msg"`
+	Data     T      `json:"data"`
+}
+
+// Any 用于 Swagger 文档的响应类型（非泛型）
+// swag 不支持泛型，使用此类型替代 Response[T]
+type Any struct {
+	ErrorMsg string      `json:"error_msg" example:""`
+	Data     interface{} `json:"data"`
+}
+
+// OK 构造成功响应
+func OK[T any](data T) Response[T] {
+	return Response[T]{Data: data}
+}
+
+// OKNil 构造成功响应（data 为 null）
+func OKNil() Response[any] {
+	return Response[any]{Data: nil}
+}
+
+// Err 构造错误响应
+func Err(msg string) Response[any] {
+	return Response[any]{ErrorMsg: msg, Data: nil}
+}