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/ai_agent_service_test.go

@@ -32,7 +32,7 @@ func TestUpdateAIAgentKeepsPublishedRevisionActive(t *testing.T) {
 			_ = sqlDB.Close()
 		}
 	})
-	if err := db.AutoMigrate(&models.AIConfig{}, &models.AIAgent{}, &models.AIAgentWorkflowBinding{}); err != nil {
+	if err := db.AutoMigrate(&models.AIConfig{}, &models.AIAgent{}); err != nil {
 		t.Fatalf("auto migrate: %v", err)
 	}
 	sqls.SetDB(db)
@@ -46,6 +46,7 @@ func TestUpdateAIAgentKeepsPublishedRevisionActive(t *testing.T) {
 	}
 	createdModel, err := AIAgentService.buildAIAgentModel(0, request.CreateAIAgentRequest{
 		Name:         "fixed ai reception agent",
+		Avatar:       " https://cdn.example.com/agent.png ",
 		AIConfigID:   config.ID,
 		ServiceMode:  enums.IMConversationServiceModeHumanOnly,
 		HandoffMode:  enums.AIAgentHandoffModeWaitPool,
@@ -57,6 +58,9 @@ func TestUpdateAIAgentKeepsPublishedRevisionActive(t *testing.T) {
 	if createdModel.ServiceMode != enums.IMConversationServiceModeAIFirst {
 		t.Fatalf("service mode = %d, want AI first", createdModel.ServiceMode)
 	}
+	if createdModel.Avatar != "https://cdn.example.com/agent.png" {
+		t.Fatalf("avatar = %q, want trimmed avatar URL", createdModel.Avatar)
+	}
 	agent := &models.AIAgent{
 		Name: "published agent", Status: enums.StatusOk, AIConfigID: config.ID,
 		ServiceMode: enums.IMConversationServiceModeAIFirst, HandoffMode: enums.AIAgentHandoffModeWaitPool,
@@ -69,7 +73,7 @@ func TestUpdateAIAgentKeepsPublishedRevisionActive(t *testing.T) {
 	err = AIAgentService.UpdateAIAgent(request.UpdateAIAgentRequest{
 		ID: agent.ID,
 		CreateAIAgentRequest: request.CreateAIAgentRequest{
-			Name: "updated draft", AIConfigID: config.ID,
+			Name: "updated draft", Avatar: "https://cdn.example.com/updated.png", AIConfigID: config.ID,
 			ServiceMode:    enums.IMConversationServiceModeAIFirst,
 			HandoffMode:    enums.AIAgentHandoffModeWaitPool,
 			FallbackMode:   enums.AIAgentFallbackModeNoAnswer,
@@ -90,4 +94,7 @@ func TestUpdateAIAgentKeepsPublishedRevisionActive(t *testing.T) {
 	if updated.Name != "updated draft" {
 		t.Fatalf("draft name = %q, want updated draft", updated.Name)
 	}
+	if updated.Avatar != "https://cdn.example.com/updated.png" {
+		t.Fatalf("draft avatar = %q, want updated avatar", updated.Avatar)
+	}
 }