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/ai/runtime/reply_commit_service_test.go

@@ -1,6 +1,7 @@
 package runtime
 
 import (
+	"context"
 	"strings"
 	"testing"
 	"time"
@@ -14,18 +15,17 @@ import (
 	"gorm.io/gorm/schema"
 )
 
-func TestReplyCommitStoresWorkflowRunIDOnAIMessage(t *testing.T) {
+func TestReplyCommitStoresAIMessage(t *testing.T) {
 	db := setupReplyCommitTestDB(t)
 	aiAgent := createReplyCommitTestAIAgent(t, db)
 	conversation := createReplyCommitTestConversation(t, db, aiAgent.ID)
 
 	replyMessage, err := newReplyCommitService().CommitAIReply(replyCommitInput{
-		Conversation:  *conversation,
-		Message:       models.Message{ID: 101, RequestID: "trace-101"},
-		AIAgent:       *aiAgent,
-		ReplyText:     "AI reply",
-		ClientPrefix:  "ai_reply",
-		WorkflowRunID: 9988,
+		Conversation: *conversation,
+		Message:      models.Message{ID: 101, RequestID: "trace-101"},
+		AIAgent:      *aiAgent,
+		ReplyText:    "AI reply",
+		ClientPrefix: "ai_reply",
 	})
 	if err != nil {
 		t.Fatalf("CommitAIReply() error = %v", err)
@@ -33,16 +33,12 @@ func TestReplyCommitStoresWorkflowRunIDOnAIMessage(t *testing.T) {
 	if replyMessage == nil {
 		t.Fatalf("expected reply message")
 	}
-	if replyMessage.WorkflowRunID != 9988 {
-		t.Fatalf("replyMessage.WorkflowRunID=%d want 9988", replyMessage.WorkflowRunID)
-	}
-
 	var stored models.Message
 	if err := db.First(&stored, replyMessage.ID).Error; err != nil {
 		t.Fatalf("find reply message: %v", err)
 	}
-	if stored.WorkflowRunID != 9988 {
-		t.Fatalf("stored.WorkflowRunID=%d want 9988", stored.WorkflowRunID)
+	if stored.Content != "AI reply" || stored.RequestID != "trace-101" {
+		t.Fatalf("unexpected stored reply: %#v", stored)
 	}
 }
 
@@ -66,6 +62,28 @@ func TestReplyCommitRejectsSensitiveModelOutput(t *testing.T) {
 	}
 }
 
+func TestFailureReplyDeduplicatesByDeterministicClientMessageID(t *testing.T) {
+	db := setupReplyCommitTestDB(t)
+	aiAgent := createReplyCommitTestAIAgent(t, db)
+	conversation := createReplyCommitTestConversation(t, db, aiAgent.ID)
+	message := models.Message{ID: 103, ConversationID: conversation.ID, RequestID: "trace-shared"}
+	service := newAIReplyService()
+
+	service.commitFailureReplyIfNeeded(*conversation, message, *aiAgent, context.DeadlineExceeded)
+	// The request ID is deliberately changed: error idempotency is tied to the
+	// triggering customer message, not a transport trace that can be regenerated.
+	message.RequestID = "trace-retry"
+	service.commitFailureReplyIfNeeded(*conversation, message, *aiAgent, context.DeadlineExceeded)
+
+	var messages []models.Message
+	if err := db.Where("conversation_id = ? AND client_msg_id = ?", conversation.ID, "ai_error_103").Find(&messages).Error; err != nil {
+		t.Fatalf("find failure messages: %v", err)
+	}
+	if len(messages) != 1 {
+		t.Fatalf("failure reply count = %d, want 1", len(messages))
+	}
+}
+
 func setupReplyCommitTestDB(t *testing.T) *gorm.DB {
 	t.Helper()
 	dbName := "reply_commit_test_" + strings.NewReplacer("/", "_").Replace(t.Name())