refactor(frontend): split 7 oversized pages into feature co-location

Per guide ch.7 page split pattern (skeleton orchestrates, private
components live in features/<domain>/):
- InstancePage 1716->328, UsersPage 1309->240, TicketsPage 1076->195,
  TicketDetailPage 911->287, QueriesPage 883->479, LdapConfigPage 860->393,
  WorkflowPage 852->194
- new feature modules: datasource/ rbac/ ticket/ query/ system/ldap/
  governance/workflow/ (components + hooks + types + utils)
- stable keys replace index keys in dynamic lists; polling intervals
  and toast call sites preserved 1:1 (verified by agents)
- filter/pagination state moved to URL query via new useQueryState hook
  (Instance/Users/Tickets/AuditLogs pages): refresh/share/back-button
  restore state; composite updates applied atomically
- permission pure functions extracted to lib/permissions.ts (used by
  useAuth + useLogin); page-size audit: 0 pages over 700-line budget

frontend/src/features/rbac/hooks/useUserSelection.ts

@@ -0,0 +1,35 @@
+/**
+ * 用途:管理用户表格的多选状态(单选切换 / 全选切换 / 选中集合)
+ * 必需参数:visible(当前可见的用户列表,用于计算全选状态)
+ * 已知限制:翻页或刷新后不自动清除选中(与原页面行为一致,由调用方决定何时清空)
+ */
+
+import { useState } from 'react';
+import type { UserItem } from '../types';
+
+export function useUserSelection(visible: UserItem[]) {
+  const [selectedIds, setSelectedIds] = useState<Set<number>>(new Set());
+
+  const allSelected = visible.length > 0 && visible.every(u => selectedIds.has(u.id));
+
+  const toggleSelectAll = () => {
+    if (allSelected) {
+      const next = new Set(selectedIds);
+      visible.forEach(u => next.delete(u.id));
+      setSelectedIds(next);
+    } else {
+      const next = new Set(selectedIds);
+      visible.forEach(u => next.add(u.id));
+      setSelectedIds(next);
+    }
+  };
+
+  const toggleSelect = (id: number) => {
+    const next = new Set(selectedIds);
+    if (next.has(id)) next.delete(id);
+    else next.add(id);
+    setSelectedIds(next);
+  };
+
+  return { selectedIds, setSelectedIds, allSelected, toggleSelectAll, toggleSelect };
+}

frontend/src/features/rbac/hooks/useUsersList.ts

@@ -0,0 +1,47 @@
+/**
+ * 用途:按分页与筛选条件拉取用户列表(参数组装与后端接口保持原样)
+ * 必需参数:page / pageSize / search / roleFilter / statusFilter
+ * 已知限制:来源(sourceFilter)为前端过滤,不参与请求;失败时 toast 必现
+ */
+
+import { useState, useEffect, useCallback } from 'react';
+import { userApi } from '@/api/user';
+import { toast } from '@/hooks/useToast';
+import type { UserItem } from '../types';
+
+export interface UseUsersListParams {
+  page: number;
+  pageSize: number;
+  search: string;
+  roleFilter: string;
+  statusFilter: string;
+}
+
+export function useUsersList({ page, pageSize, search, roleFilter, statusFilter }: UseUsersListParams) {
+  const [users, setUsers] = useState<UserItem[]>([]);
+  const [total, setTotal] = useState(0);
+  const [loading, setLoading] = useState(false);
+
+  const fetchUsers = useCallback(async () => {
+    setLoading(true);
+    try {
+      const params: any = { page, page_size: pageSize };
+      if (search) params.search = search;
+      if (roleFilter) params.role = roleFilter;
+      if (statusFilter === 'active') params.is_active = true;
+      else if (statusFilter === 'disabled') params.is_active = false;
+      const res = await userApi.list(params);
+      const data = res as any;
+      setUsers(Array.isArray(data?.items) ? data.items : Array.isArray(data) ? data : []);
+      setTotal(data?.total ?? data?.length ?? 0);
+    } catch {
+      toast('error', '获取用户列表失败');
+    } finally {
+      setLoading(false);
+    }
+  }, [page, pageSize, search, roleFilter, statusFilter]);
+
+  useEffect(() => { fetchUsers(); }, [fetchUsers]);
+
+  return { users, total, loading, fetchUsers };
+}