feedback7 stats: the local statistics page, ported from PR #323 by @2321Robin as submitted (record store ui/stats.js, viewer screens/stats.js, stats.css, entries on the title / lobby / room screens, 20 tests); golden: unchanged

- public/js/ui/stats.js: one record per finished match in localStorage (sp.pref.stats, envelope {v, records}, at most
  1000, quota shrink of the oldest), content-id dedupe of the lobby's result replay, a MIGRATIONS chain and
  normalizeRecord (defaults for missing fields, unknown fields kept, a newer envelope refused), merge-by-id export /
  import, aggregateStats.
- public/js/screens/stats.js: the viewer (总览 / 策略 / 称号 / 战斗累计 / 最近对局, a row re-views that match's
  settlement), 导出 / 导入 / 清空.
- Applied from the PR's own diff after reading it in full (no network, no new dependency, server untouched); only the
  UI strings of the page are added to the four packs (en from the PR; ja / ko / zh-TW translated for this commit).
- The follow-up commits rework the page (the counting rule for matches left early, storage bounds, the layout).
- Tests: test/ui/stats.test.js 20 / 20; i18n extract 0, check --all --strict clean.

public/js/screens/lobby.js

@@ -16,6 +16,7 @@ import { DIFFICULTIES, DIFFICULTY_NAMES, DIFFICULTY_COLORS, ROOM_CODE_LEN, MAX_S
 import { html, Button, Icon, MicroLabel, Panel, TextField, PingPill, AvatarFrame, Tooltip, Spinner, DifficultyIcon, doctorNo } from '../ui/components.js';
 import { toast, toastError } from '../ui/toasts.js';
 import { GuideButton } from '../ui/guide.js';
+import { openStats } from './stats.js';
 import { LoadoutButton } from './loadout.js';
 import { net, identity } from '../net.js';
 import { store, useStore, shallowEqual, loadPref, savePref } from '../store.js';
@@ -311,6 +312,7 @@ export function LobbyScreen() {
         <h1 class="topbar__title">${t('选择模拟协议')}</h1>
       </div>
       <div class="topbar__right">
+        <${Button} variant="secondary" size="sm" icon="signal" onClick=${openStats} title=${t('统计数据')}>${t('统计')}<//>
         <${GuideButton} class="lobby-guide" variant="secondary" label=${t('玩法说明')} />
         <${LoadoutButton} from="lobby" size="sm" class="lobby-loadout" label=${t('干员调配')} />
         <div class="me-chip">