fix: AuditRulesPage白屏修复 + 数据源权限/状态对齐

- AuditRulesPage: rules/stats 空值防御, catch 时设置空数组/null
- instance.add 权限: admin → admin+dba (与后端一致)
- 状态映射: 后端 connected/disconnected/error → 前端在线/离线/异常
- InstancePage 所有状态引用统一使用 getStatusInfo()

frontend/src/hooks/useAuth.tsx

@@ -62,7 +62,7 @@ export const actionPermissionMap: Record<string, UserRole[]> = {
   'ticket.delete': ['admin'],
   'query.create': ['admin', 'dba', 'developer'],
   'query.export': ['admin', 'dba', 'developer'],
-  'instance.add': ['admin'],
+  'instance.add': ['admin', 'dba'],
   'instance.edit': ['admin', 'dba'],
   'instance.delete': ['admin'],
   'user.manage': ['admin'],