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/bootstrap/db.go

@@ -4,18 +4,13 @@ import (
 	"fmt"
 	"log"
 	"os"
-	"path/filepath"
 	"strings"
 	"time"
 
 	"code.tczkiot.com/wlw/ai-agent/internal/pkg/config"
 
 	"github.com/mlogclub/simple/sqls"
-	"gorm.io/driver/mysql"
 	"gorm.io/driver/postgres"
-
-	// "gorm.io/driver/sqlite" // Sqlite driver based on CGO
-	"github.com/glebarez/sqlite" // Pure go SQLite driver, checkout https://github.com/glebarez/sqlite for details
 	"gorm.io/gorm"
 
 	// "gorm.io/gorm/logger"
@@ -69,50 +64,39 @@ func InitDB(cfg config.DBConfig) (*gorm.DB, error) {
 	return db, nil
 }
 
+// UseDatabase scopes the host application's connection to AI Agent tables.
+// The connection pool is shared, while the naming strategy is copied so the
+// host database naming rules remain untouched.
+func UseDatabase(database *gorm.DB, tablePrefix string) error {
+	moduleDB, err := ScopedDatabase(database, tablePrefix)
+	if err != nil {
+		return err
+	}
+	sqls.SetDB(moduleDB)
+	return nil
+}
+
+// ScopedDatabase shares the host connection pool while applying the AI Agent
+// table prefix to an isolated GORM session.
+func ScopedDatabase(database *gorm.DB, tablePrefix string) (*gorm.DB, error) {
+	if database == nil {
+		return nil, fmt.Errorf("database is required")
+	}
+	moduleDB := database.Session(&gorm.Session{NewDB: true})
+	moduleConfig := *moduleDB.Config
+	moduleConfig.NamingStrategy = schema.NamingStrategy{
+		TablePrefix:   tablePrefix,
+		SingularTable: true,
+	}
+	moduleDB.Config = &moduleConfig
+	return moduleDB, nil
+}
+
 func newDialector(cfg config.DBConfig) (gorm.Dialector, error) {
 	switch strings.ToLower(strings.TrimSpace(cfg.Type)) {
-	case "sqlite":
-		if err := ensureSQLiteDir(cfg.DSN); err != nil {
-			return nil, err
-		}
-		return sqlite.Open(cfg.DSN), nil
-	case "mysql":
-		return mysql.Open(cfg.DSN), nil
 	case "postgres", "postgresql":
 		return postgres.Open(cfg.DSN), nil
 	default:
-		return nil, fmt.Errorf("unsupported db type: %s", cfg.Type)
+		return nil, fmt.Errorf("unsupported db type %q: only postgres is supported", cfg.Type)
 	}
 }
-
-func ensureSQLiteDir(dsn string) error {
-	dbPath := sqliteFilePath(dsn)
-	if dbPath == "" {
-		return nil
-	}
-	dir := filepath.Dir(dbPath)
-	if dir == "." || dir == "" {
-		return nil
-	}
-	return os.MkdirAll(dir, 0o755)
-}
-
-func sqliteFilePath(dsn string) string {
-	if dsn == "" {
-		return ""
-	}
-
-	path := dsn
-	if after, ok := strings.CutPrefix(path, "file:"); ok {
-		path = after
-	}
-	if idx := strings.Index(path, "?"); idx >= 0 {
-		path = path[:idx]
-	}
-
-	normalized := strings.TrimSpace(path)
-	if normalized == "" || normalized == ":memory:" || strings.Contains(normalized, "mode=memory") {
-		return ""
-	}
-	return normalized
-}