fix: 统计概览接口补充 expenseCount/incomeCount/dailyIncome 字段

- 后端 stats/overview 接口返回字段与前端 Overview 类型不一致
- 前端页面使用了 expenseCount、incomeCount、dailyIncome 但后端未返回
- 导致统计页收入标签切换时日均和笔数显示为 0
- 补充 SQL 聚合查询，返回完整字段

server/src/routes/stats.ts

@@ -72,16 +72,27 @@ router.get('/overview', async (req: AuthRequest, res: Response) => {
       `SELECT
         COALESCE(SUM(CASE WHEN t.type = 'expense' THEN t.amount ELSE 0 END), 0) as expense,
         COALESCE(SUM(CASE WHEN t.type = 'income' THEN t.amount ELSE 0 END), 0) as income,
-        COUNT(*) as count
+        COUNT(*) as count,
+        SUM(CASE WHEN t.type = 'expense' THEN 1 ELSE 0 END) as expenseCount,
+        SUM(CASE WHEN t.type = 'income' THEN 1 ELSE 0 END) as incomeCount
        FROM transactions t ${result.where}`,
       [...result.params, startDate, endDate]
     )
     const row = (rows as any[])[0]
     const daily = elapsedDays > 0 ? Math.round(row.expense / elapsedDays) : 0
+    const dailyIncome = elapsedDays > 0 ? Math.round(row.income / elapsedDays) : 0
 
     res.json({
       code: 0,
-      data: { expense: row.expense, income: row.income, count: row.count, daily }
+      data: {
+        expense: row.expense,
+        income: row.income,
+        count: row.count,
+        daily,
+        dailyIncome,
+        expenseCount: row.expenseCount,
+        incomeCount: row.incomeCount
+      }
     })
   } catch (err) {
     console.error('[Stats] overview error:', err)