fix: 修复日期范围选择器时区和性能问题

- 修复时区问题：使用本地时区格式化日期，避免 toISOString() 导致的日期偏移
- 优化日期范围选择器性能：使用 untrack 避免循环更新
- 统一日期格式化方法：在 utils.ts 中添加 formatLocalDate 工具函数
- 修复分页逻辑：优化页码计算和显示
- 更新相关页面：bills 和 analysis 页面使用统一的日期格式化方法

web/src/routes/analysis/+page.svelte

@@ -5,6 +5,7 @@
   import { Badge } from '$lib/components/ui/badge';
   import * as Card from '$lib/components/ui/card';
   import { DateRangePicker } from '$lib/components/ui/date-range-picker';
+  import { formatLocalDate } from '$lib/utils';
   import BarChart3 from '@lucide/svelte/icons/bar-chart-3';
   import Loader2 from '@lucide/svelte/icons/loader-2';
   import AlertCircle from '@lucide/svelte/icons/alert-circle';
@@ -41,8 +42,9 @@
     const today = new Date();
     const year = today.getFullYear();
     const month = today.getMonth();
-    const startDate = new Date(year, month, 1).toISOString().split('T')[0];
-    const endDate = today.toISOString().split('T')[0];
+    
+    const startDate = formatLocalDate(new Date(year, month, 1));
+    const endDate = formatLocalDate(today);
     return { startDate, endDate };
   }
   const defaultDates = getDefaultDates();

web/src/routes/bills/+page.svelte

@@ -8,6 +8,7 @@
   import { Label } from '$lib/components/ui/label';
   import * as Table from '$lib/components/ui/table';
   import { DateRangePicker } from '$lib/components/ui/date-range-picker';
+  import { formatLocalDate } from '$lib/utils';
   import Loader2 from '@lucide/svelte/icons/loader-2';
   import AlertCircle from '@lucide/svelte/icons/alert-circle';
   import Search from '@lucide/svelte/icons/search';
@@ -40,8 +41,9 @@
     const today = new Date();
     const year = today.getFullYear();
     const month = today.getMonth();
-    const startDate = new Date(year, month, 1).toISOString().split('T')[0];
-    const endDate = today.toISOString().split('T')[0];
+    
+    const startDate = formatLocalDate(new Date(year, month, 1));
+    const endDate = formatLocalDate(today);
     return { startDate, endDate };
   }
   const defaultDates = getDefaultDates();
@@ -221,11 +223,9 @@
           <div class="space-y-1.5 col-span-2 sm:col-span-2">
             <Label class="text-xs">日期范围</Label>
             <DateRangePicker 
-              {startDate}
-              {endDate}
+              bind:startDate
+              bind:endDate
               onchange={(start, end) => {
-                startDate = start;
-                endDate = end;
                 applyFilters();
               }}
             />
@@ -344,6 +344,9 @@
         <div class="flex items-center justify-between mt-4">
           <p class="text-sm text-muted-foreground">
             显示 {(currentPage - 1) * pageSize + 1} - {Math.min(currentPage * pageSize, totalRecords)} 条，共 {totalRecords} 条
+            {#if searchText}
+              <span class="text-muted-foreground/70">（当前页筛选后：{displayRecords.length} 条）</span>
+            {/if}
           </p>
           <div class="flex items-center gap-2">
             <Button 
@@ -356,13 +359,17 @@
               上一页
             </Button>
             <div class="flex items-center gap-1">
-              {#each Array.from({ length: Math.min(5, totalPages) }, (_, i) => {
-                // 计算显示的页码范围
-                let start = Math.max(1, currentPage - 2);
-                let end = Math.min(totalPages, start + 4);
-                start = Math.max(1, end - 4);
-                return start + i;
-              }).filter(p => p <= totalPages) as page}
+              {#each (() => {
+                // 计算显示的页码范围（最多显示5页）
+                const maxPages = 5;
+                let start = Math.max(1, currentPage - Math.floor(maxPages / 2));
+                let end = Math.min(totalPages, start + maxPages - 1);
+                // 如果右侧空间不足，向左调整
+                if (end - start < maxPages - 1) {
+                  start = Math.max(1, end - maxPages + 1);
+                }
+                return Array.from({ length: end - start + 1 }, (_, i) => start + i);
+              })() as page}
                 <Button 
                   variant={page === currentPage ? 'default' : 'outline'}
                   size="sm"