取消游客模式，强制登录后使用

frontend/src/lib/auth.ts

@@ -30,13 +30,12 @@ export function clearAuth() {
   localStorage.removeItem('user')
 }
 
-export type RoleName = 'system_admin' | 'admin' | 'user' | 'guest'
+export type RoleName = 'system_admin' | 'admin' | 'user'
 
 const ROLE_RANK: Record<RoleName, number> = {
   system_admin: 3,
   admin: 2,
   user: 1,
-  guest: 0,
 }
 
 export function roleRank(role: RoleName): number {
@@ -51,8 +50,6 @@ export function roleLabel(role: RoleName): string {
       return '管理员'
     case 'user':
       return '用户'
-    case 'guest':
-      return '游客'
   }
 }