refactor: 将客服后端重构为宿主可嵌入模块

- 注入数据库、运行时配置、统一响应、文件存储和平台 AI 能力，补充业务读写工具与客户快捷操作契约。

- 移除模块内重复的组织、客户、工单、标签、技能、旧工作流、MCP 和迁移实现，将身份权限与业务主体交由宿主管理。

- 使用 libSQL 重构向量存储，并完善图片消息、访客身份、排队调度、企业微信和支持聊天页面。

- 统一 HTTP、DTO 与 WebSocket 的 snake_case 协议，补齐模块初始化、业务动作和公共载荷等回归测试。

internal/services/notification_service_test.go

@@ -18,12 +18,12 @@ func TestNotificationServiceCreateAndUnreadCount(t *testing.T) {
 
 	item, err := services.NotificationService.Create(request.CreateNotificationRequest{
 		RecipientUserID:  101,
-		Title:            "工单指派提醒",
-		Content:          "工单 TK-1 已指派给你",
-		NotificationType: "ticket_assigned",
-		BizType:          "ticket",
+		Title:            "会话分配提醒",
+		Content:          "会话 #1 已分配给你",
+		NotificationType: "conversation_assigned",
+		BizType:          "conversation",
 		BizID:            1,
-		ActionURL:        "/dashboard/tickets/1",
+		ActionURL:        "/dashboard/conversations?conversationId=1",
 	})
 	if err != nil {
 		t.Fatalf("Create() error = %v", err)
@@ -78,12 +78,12 @@ func TestNotificationServiceMarkAllReadOnlyCurrentUser(t *testing.T) {
 	for _, userID := range []int64{301, 301, 302} {
 		if _, err := services.NotificationService.Create(request.CreateNotificationRequest{
 			RecipientUserID:  userID,
-			Title:            "工单指派提醒",
-			Content:          "工单已指派给你",
-			NotificationType: "ticket_assigned",
-			BizType:          "ticket",
+			Title:            "会话分配提醒",
+			Content:          "会话已分配给你",
+			NotificationType: "conversation_assigned",
+			BizType:          "conversation",
 			BizID:            userID,
-			ActionURL:        "/dashboard/tickets/1",
+			ActionURL:        "/dashboard/conversations?conversationId=1",
 		}); err != nil {
 			t.Fatalf("Create() error = %v", err)
 		}