refactor(auth): modularize auth plugin with physical subpackages and decoupled services

backend/plugins/domain/auth/model/dto/auth_source.go

@@ -0,0 +1,45 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package dto provides data transfer objects and views for the auth plugin.
+package dto
+
+// AuthSourceView 登录源展示信息
+type AuthSourceView struct {
+	ID                     uint64 `json:"id"`
+	Name                   string `json:"name"`
+	Type                   string `json:"type"`
+	DisplayName            string `json:"display_name"`
+	IsActive               bool   `json:"is_active"`
+	IconURL                string `json:"icon_url"`
+	ClientSecretConfigured bool   `json:"client_secret_configured"`
+}
+
+// OAuthAuthorizeResponse 授权 URL 响应
+type OAuthAuthorizeResponse struct {
+	AuthorizeURL string `json:"authorize_url"`
+}
+
+// OAuthCallbackResult 回调处理结果
+type OAuthCallbackResult struct {
+	Status string         `json:"status"`
+	User   *BasicUserInfo `json:"user,omitempty"`
+}
+
+// CallbackRequest OAuth 回调请求参数
+type CallbackRequest struct {
+	State string `json:"state" binding:"required"`
+	Code  string `json:"code" binding:"required"`
+}
+
+// ExternalAccountView 外部帐号绑定视图（脱敏展示用）
+type ExternalAccountView struct {
+	ID               uint64 `json:"id"`
+	AuthSourceID     uint64 `json:"auth_source_id"`
+	AuthSourceName   string `json:"auth_source_name"`
+	AuthSourceType   string `json:"auth_source_type"`
+	AuthSourceLabel  string `json:"auth_source_label"`
+	ExternalUsername string `json:"external_username"`
+	Email            string `json:"email"`
+	CreatedAt        string `json:"created_at"`
+}