feat(analysis): 增强图表交互功能

- 分类支出排行: 饼图支持点击类别切换显示/隐藏，百分比动态重新计算
- 每日支出趋势: 图例支持点击切换类别显示，隐藏类别不参与堆叠计算
- Dialog列表: 添加列排序功能（时间/商家/描述/金额）
- Dialog列表: 添加分页功能，每页10条（分类）/8条（每日）
- 饼图hover效果: 扇形放大、阴影增强、中心显示详情

web/src/lib/services/analysis.ts

@@ -0,0 +1,129 @@
+import type { BillRecord } from '$lib/api';
+import type { CategoryStat, MonthlyStat, DailyExpenseData, TotalStats, PieChartDataItem } from '$lib/types/analysis';
+import { pieColors } from '$lib/constants/chart';
+
+/**
+ * 计算分类统计
+ */
+export function calculateCategoryStats(records: BillRecord[]): CategoryStat[] {
+  const stats = new Map<string, { expense: number; income: number; count: number }>();
+  
+  for (const r of records) {
+    if (!stats.has(r.category)) {
+      stats.set(r.category, { expense: 0, income: 0, count: 0 });
+    }
+    const s = stats.get(r.category)!;
+    s.count++;
+    const amount = parseFloat(r.amount || '0');
+    if (r.income_expense === '支出') {
+      s.expense += amount;
+    } else {
+      s.income += amount;
+    }
+  }
+  
+  return [...stats.entries()]
+    .map(([category, data]) => ({ category, ...data }))
+    .sort((a, b) => b.expense - a.expense);
+}
+
+/**
+ * 计算月度统计
+ */
+export function calculateMonthlyStats(records: BillRecord[]): MonthlyStat[] {
+  const stats = new Map<string, { expense: number; income: number }>();
+  
+  for (const r of records) {
+    const month = r.time.substring(0, 7); // YYYY-MM
+    if (!stats.has(month)) {
+      stats.set(month, { expense: 0, income: 0 });
+    }
+    const s = stats.get(month)!;
+    const amount = parseFloat(r.amount || '0');
+    if (r.income_expense === '支出') {
+      s.expense += amount;
+    } else {
+      s.income += amount;
+    }
+  }
+  
+  return [...stats.entries()]
+    .map(([month, data]) => ({ month, ...data }))
+    .sort((a, b) => a.month.localeCompare(b.month));
+}
+
+/**
+ * 计算每日支出数据（用于面积图）
+ */
+export function calculateDailyExpenseData(records: BillRecord[]): DailyExpenseData[] {
+  const stats = new Map<string, number>();
+  
+  for (const r of records) {
+    if (r.income_expense !== '支出') continue;
+    const date = r.time.substring(0, 10); // YYYY-MM-DD
+    const amount = parseFloat(r.amount || '0');
+    stats.set(date, (stats.get(date) || 0) + amount);
+  }
+  
+  return [...stats.entries()]
+    .map(([date, value]) => ({ date: new Date(date), value }))
+    .sort((a, b) => a.date.getTime() - b.date.getTime());
+}
+
+/**
+ * 计算总计统计
+ */
+export function calculateTotalStats(records: BillRecord[]): TotalStats {
+  return {
+    expense: records
+      .filter(r => r.income_expense === '支出')
+      .reduce((sum, r) => sum + parseFloat(r.amount || '0'), 0),
+    income: records
+      .filter(r => r.income_expense === '收入')
+      .reduce((sum, r) => sum + parseFloat(r.amount || '0'), 0),
+    count: records.length,
+  };
+}
+
+/**
+ * 计算百分比
+ */
+export function getPercentage(value: number, total: number): number {
+  return total > 0 ? (value / total) * 100 : 0;
+}
+
+/**
+ * 计算饼状图数据
+ */
+export function calculatePieChartData(
+  categoryStats: CategoryStat[], 
+  totalExpense: number
+): PieChartDataItem[] {
+  return categoryStats
+    .filter(s => s.expense > 0)
+    .map((stat, i) => ({
+      category: stat.category,
+      value: stat.expense,
+      color: pieColors[i % pieColors.length],
+      percentage: getPercentage(stat.expense, totalExpense)
+    }));
+}
+
+/**
+ * 获取 Top N 支出记录
+ */
+export function getTopExpenses(records: BillRecord[], n: number = 10): BillRecord[] {
+  return records
+    .filter(r => r.income_expense === '支出')
+    .sort((a, b) => parseFloat(b.amount) - parseFloat(a.amount))
+    .slice(0, n);
+}
+
+/**
+ * 统计支出/收入笔数
+ */
+export function countByType(records: BillRecord[], type: '支出' | '收入'): number {
+  return records.filter(r => r.income_expense === type).length;
+}
+
+