feedback7: merge fb7-stats — the local statistics page (PR #323 by @2321Robin, reworked): a match counts when it reached its result or the player cleared at least one round before quitting; earlier quits stay in the history marked 中途退出 / 不计入统计 (the owner's rule of 2026-10-08)

- Conflict: docs/PLAYING.md — #321's §12 反馈问题 and the stats §12 both added; the stats section is §13 (README anchor
  updated).
- Golden unchanged; broad node --test 5382 (5381 pass, 0 fail, 1 skipped); lint 0 errors.

public/js/screens/room.js

@@ -19,6 +19,7 @@ import {
 import { toast, toastError } from '../ui/toasts.js';
 import { copyText } from '../ui/clipboard.js';
 import { GuideButton } from '../ui/guide.js';
+import { openStats } from './stats.js';
 import { LoadoutButton } from './loadout.js';
 import { net } from '../net.js';
 import { store, useStore, shallowEqual, emptyMatch, isSpectating } from '../store.js';
@@ -306,6 +307,7 @@ export function RoomScreen() {
           <${PingPill} ms=${conn.ping} online=${online} />
           <${MicroLabel}>${t('当前延迟')}<//>
         </div>
+        <${Button} variant="secondary" size="sm" icon="chart" class="stats-entry" onClick=${openStats} title=${t('统计数据')} aria-label=${t('统计数据')}>${t('统计')}<//>
         <${GuideButton} class="room-guide" variant="secondary" label=${t('玩法说明')} />
       </div>
       <div class="topbar__center">