fix(前端): 修复成员表头与加班导出

关键改动：

- 成员管理表格改为卡片内滚动，并固定每个表头单元格

- 加班导出按当前月份筛选导出记录

- 增加成员表头与加班导出月份过滤测试

Co-Authored-By: Codex GPT-5 <codex@openai.com>

apps/web/lib/overtime.test.ts

@@ -1,12 +1,13 @@
-import assert from 'node:assert/strict';
 import test from 'node:test';
+import assert from 'node:assert/strict';
 
 import {
+  filterOvertimeRecordsForExportMonth,
   filterOvertimeRecordsForViewer,
   type OvertimeRecord,
 } from './overtime';
-import type { Department, Member, RoleItem } from './members';
 import type { AuthUser } from './auth-user';
+import type { Department, Member, RoleItem } from './members';
 
 const departments: Department[] = [
   { id: 'dept-tech', name: 'Tech', order: 1, createdAt: '2024-01-01' },
@@ -28,6 +29,29 @@ const records: OvertimeRecord[] = [
   record('ot-pm', 'PM Carol'),
 ];
 
+const exportRecords: OvertimeRecord[] = [
+  {
+    id: 'july-1',
+    projectId: 'project-1',
+    person: 'Alice',
+    startTime: '2026-07-01T19:00:00',
+    endTime: '2026-07-01T21:00:00',
+    duration: 2,
+    reasonId: 'reason-1',
+    createdAt: '2026-07-01',
+  },
+  {
+    id: 'august-1',
+    projectId: 'project-1',
+    person: 'Bob',
+    startTime: '2026-08-02T19:00:00',
+    endTime: '2026-08-02T21:00:00',
+    duration: 2,
+    reasonId: 'reason-1',
+    createdAt: '2026-08-02',
+  },
+];
+
 test('filterOvertimeRecordsForViewer limits non-admin viewers to their department tree', () => {
   const visible = filterOvertimeRecordsForViewer(records, {
     viewer: toAuthUser(members[0]),
@@ -50,6 +74,18 @@ test('filterOvertimeRecordsForViewer lets wildcard admin view every department',
   assert.deepEqual(visible.map((item) => item.id), ['ot-front', 'ot-back', 'ot-pm']);
 });
 
+test('filters export records by selected month', () => {
+  const result = filterOvertimeRecordsForExportMonth(exportRecords, '2026-07');
+
+  assert.deepEqual(result.map((record) => record.id), ['july-1']);
+});
+
+test('keeps all export records when all months are selected', () => {
+  const result = filterOvertimeRecordsForExportMonth(exportRecords, '');
+
+  assert.deepEqual(result.map((record) => record.id), ['july-1', 'august-1']);
+});
+
 function member(id: string, name: string, departmentId: string, roleId: string): Member {
   return {
     id,