优化: 前后端字段对齐、AI分析JSON解析修复、AutoMigrate

- 修复登录参数 username→account
- 修复前后端字段名不匹配 (ticketno/contactname/createtime等)
- 修复AI分析GLM返回markdown包裹和priority类型问题
- 添加AutoMigrate自动建表
- 统一API路由为 /api/auth/ 前缀
- 添加config.example.yaml，.gitignore排除config.yaml

backend/internal/service/auth_service.go

@@ -4,13 +4,17 @@ import (
 	"crypto/md5"
 	"encoding/hex"
 	"fmt"
+	"sync"
 
 	"github.com/casehub/ticket-workbench/internal/model"
 	"github.com/google/uuid"
 	"gorm.io/gorm"
 )
 
-var sessions = make(map[string]*model.TicketUser)
+var (
+	sessions  = make(map[string]*model.TicketUser)
+	sessionMu sync.RWMutex
+)
 
 func MD5Hash(text string) string {
 	hash := md5.Sum([]byte(text))
@@ -32,15 +36,21 @@ func Login(db *gorm.DB, account, password string) (*model.TicketUser, string, er
 	}
 
 	sessionID := uuid.New().String()
+	sessionMu.Lock()
 	sessions[sessionID] = &user
+	sessionMu.Unlock()
 
 	return &user, sessionID, nil
 }
 
 func Logout(sessionID string) {
+	sessionMu.Lock()
 	delete(sessions, sessionID)
+	sessionMu.Unlock()
 }
 
 func GetUserBySession(sessionID string) *model.TicketUser {
+	sessionMu.RLock()
+	defer sessionMu.RUnlock()
 	return sessions[sessionID]
 }