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/builders/conversation_builder_test.go

@@ -102,21 +102,6 @@ func TestLocalizeRenderableMessageContent(t *testing.T) {
 	}
 }
 
-func TestBuildMessageIncludesWorkflowRunID(t *testing.T) {
-	resp := BuildMessageWithReadStatesAndLocale(&models.Message{
-		ID:             1,
-		ConversationID: 2,
-		SenderType:     enums.IMSenderTypeAI,
-		MessageType:    enums.IMMessageTypeText,
-		Content:        "AI reply",
-		WorkflowRunID:  9988,
-	}, nil, nil, nil, nil, nil, i18nx.DefaultLocale)
-
-	if resp.WorkflowRunID != 9988 {
-		t.Fatalf("resp.WorkflowRunID=%d want 9988", resp.WorkflowRunID)
-	}
-}
-
 func TestBuildMessageJSONDoesNotExposeSeqNo(t *testing.T) {
 	resp := BuildMessageWithReadStatesAndLocale(&models.Message{
 		ID:             1,
@@ -134,3 +119,24 @@ func TestBuildMessageJSONDoesNotExposeSeqNo(t *testing.T) {
 		t.Fatalf("message response should not expose seqNo, got %s", raw)
 	}
 }
+
+func TestBuildAIMessageIncludesAgentAvatar(t *testing.T) {
+	const avatar = "https://cdn.example.com/ai-agent.png"
+	resp := BuildMessageWithReadStatesAndLocale(&models.Message{
+		ID:             3,
+		ConversationID: 2,
+		SenderType:     enums.IMSenderTypeAI,
+		SenderID:       9,
+		MessageType:    enums.IMMessageTypeText,
+		Content:        "hello",
+	}, nil, nil, map[int64]*models.AIAgent{
+		9: {ID: 9, Name: "AI 客服", Avatar: avatar},
+	}, nil, nil, i18nx.DefaultLocale)
+
+	if resp.SenderName != "AI 客服" {
+		t.Fatalf("sender name = %q, want AI 客服", resp.SenderName)
+	}
+	if resp.SenderAvatar != avatar {
+		t.Fatalf("sender avatar = %q, want %q", resp.SenderAvatar, avatar)
+	}
+}