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

backend/plugins/domain/auth/model/entity/external_account.go

@@ -0,0 +1,26 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package entity provides database model entities for the auth domain plugin.
+package entity
+
+import (
+	"time"
+)
+
+// ExternalAccount 外部账号绑定实体
+type ExternalAccount struct {
+	ID               uint64    `json:"id" gorm:"primaryKey"`
+	AuthSourceID     uint64    `json:"auth_source_id" gorm:"uniqueIndex:idx_external_accounts_source_external,priority:1;index"`
+	UserID           uint64    `json:"user_id" gorm:"index;not null"`
+	ExternalID       string    `json:"external_id" gorm:"uniqueIndex:idx_external_accounts_source_external,priority:2;size:255;not null"`
+	ExternalUsername string    `json:"external_username" gorm:"size:255"`
+	Email            string    `json:"email" gorm:"size:255"`
+	CreatedAt        time.Time `json:"created_at"`
+	UpdatedAt        time.Time `json:"updated_at"`
+}
+
+// TableName 表名
+func (ExternalAccount) TableName() string {
+	return "w_external_accounts"
+}