fix: AuditLogsPage暗色主题适配(20处) + 权限项前后端对齐(18→9项)

AuditLogsPage 暗色主题 P0 修复:
- ACTION_COLORS: bg-blue-100→bg-blue-500/15, text-blue-800→text-blue-400 等 8 项
- 表格容器: bg-white→dg-card, bg-gray-50→bg-[var(--dg-bg-tertiary)]
- 所有 text-gray-* → --dg-text-* 变量
- 所有 bg-gray-* → --dg-bg-* 变量
- 分隔线: divide-gray-100→divide-[var(--dg-border)]
- 分页按钮: 全部改用 dg 变量
- grep 验证: 零残留硬编码亮色

InstanceGroupPage 权限项对齐:
- 前端权限项从 18 个精简到 9 个，与后端 PERMISSION_ACTIONS 一致
- 查询: query:select, query:write
- 工单: ticket:create, ticket:approve, ticket:execute
- DDL: ddl:execute
- 运维: slowlog:view, backup:manage, instance:detail

frontend/src/pages/InstanceGroupPage.tsx

@@ -6,25 +6,13 @@ import { instanceApi } from '@/api/instance';
 import { userApi } from '@/api/user';
 import { useActionPermission } from '@/hooks/useAuth';
 
-// 权限预设
+// 权限项 — 与后端 PERMISSION_ACTIONS 保持一致
 var PERMISSION_CATEGORIES = [
   {
     label: '查询权限',
     items: [
       { code: 'query:select', name: 'SELECT 查询' },
-      { code: 'query:insert', name: 'INSERT 插入' },
-      { code: 'query:update', name: 'UPDATE 更新' },
-      { code: 'query:delete', name: 'DELETE 删除' },
-    ],
-  },
-  {
-    label: 'DDL 权限',
-    items: [
-      { code: 'ddl:create_table', name: '创建表' },
-      { code: 'ddl:alter_table', name: '修改表' },
-      { code: 'ddl:drop_table', name: '删除表' },
-      { code: 'ddl:create_index', name: '创建索引' },
-      { code: 'ddl:drop_index', name: '删除索引' },
+      { code: 'query:write', name: '写入操作 (INSERT/UPDATE/DELETE)' },
     ],
   },
   {
@@ -32,23 +20,21 @@ var PERMISSION_CATEGORIES = [
     items: [
       { code: 'ticket:create', name: '创建工单' },
       { code: 'ticket:approve', name: '审批工单' },
-      { code: 'ticket:reject', name: '拒绝工单' },
       { code: 'ticket:execute', name: '执行工单' },
     ],
   },
   {
-    label: '数据操作',
+    label: 'DDL 权限',
     items: [
-      { code: 'export:data', name: '导出数据' },
-      { code: 'import:data', name: '导入数据' },
+      { code: 'ddl:execute', name: 'DDL 执行' },
     ],
   },
   {
-    label: '管理权限',
+    label: '运维权限',
     items: [
-      { code: 'instance:connect', name: '连接实例' },
-      { code: 'instance:view_slow_query', name: '查看慢查询' },
-      { code: 'instance:kill_process', name: '终止进程' },
+      { code: 'slowlog:view', name: '查看慢日志' },
+      { code: 'backup:manage', name: '备份管理' },
+      { code: 'instance:detail', name: '实例详情' },
     ],
   },
 ];