feat: 统计页面添加分类筛选与搜索优化

- 统计页面添加分类多选筛选功能
- 点击分类可跳转到搜索页面查看详情
- 搜索页面添加 URL 同步与自动搜索
- 提取 useCategories hook 消除重复代码
- 修复自定义分类图标显示问题
- 添加 useMemo 优化计算性能

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/pages/recurring.js

@@ -1,16 +1,17 @@
 import { useState, useEffect } from 'react';
 import { useRouter } from 'next/router';
 import { isLoggedIn, getRecurringBills, createRecurringBill, updateRecurringBill, deleteRecurringBill, applyRecurringBill } from '../lib/api';
-import { DEFAULT_CATEGORIES } from '../lib/categories';
 import AppShell from '../components/AppShell';
 import { Icon } from '../components/icons';
 import { useToast } from '../components/ToastProvider';
 import { useConfirm } from '../components/ConfirmProvider';
+import { useCategories } from '../hooks/useCategories';
 
 export default function Recurring() {
   const router = useRouter();
   const { showToast } = useToast();
   const { confirm } = useConfirm();
+  const { categories } = useCategories();
   const [bills, setBills] = useState([]);
   const [modalOpen, setModalOpen] = useState(false);
   const [editingBill, setEditingBill] = useState(null);
@@ -197,8 +198,8 @@ export default function Recurring() {
           </div>
           <div className="bills-list">
             {bills.map((bill) => {
-              const categories = DEFAULT_CATEGORIES[bill.type];
-              const cat = categories.find((item) => item.name === bill.category) || { icon: '📝' };
+              const categoryList = categories[bill.type];
+              const cat = categoryList.find((item) => item.name === bill.category) || { icon: '📝' };
               return (
                 <button
                   key={bill.id}
@@ -304,7 +305,7 @@ export default function Recurring() {
               <div className="form-group">
                 <label>分类</label>
                 <div className="category-grid">
-                  {DEFAULT_CATEGORIES[formData.type].map((cat) => (
+                  {categories[formData.type].map((cat) => (
                     <button
                       key={cat.name}
                       type="button"