移除返回旧版入口和相关代码

client/src/pages/Home.tsx

@@ -36,7 +36,6 @@ import {
   Sliders,
   Activity,
   Gauge,
-  Undo2,
   Bluetooth,
   SkipBack,
   SkipForward,
@@ -195,12 +194,35 @@ export default function Home() {
   const [volumeConfirm, setVolumeConfirm] = useState<null | "min" | "max">(null);
   const [easterEggActive, setEasterEggActive] = useState(false);
   const [vuHeights, setVuHeights] = useState<number[]>(idleVuBarHeights);
+  /** 更新说明入口展示的最新版本号（取自 changelog.md 首个 "## v..." 标题） */
+  const [changelogVersion, setChangelogVersion] = useState<string | null>(null);
   const jackProgressRef = useRef(0);
   const jackResetTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
   const eggRafRef = useRef<number | null>(null);
   /** 下次三连击成功时播放的律动：1=旋律，2=海浪（各需单独三连击触发） */
   const jackEggNextRef = useRef<1 | 2>(1);
 
+  // 拉取更新说明首个版本号，静默降级（失败则入口不显示版本）
+  useEffect(() => {
+    let cancelled = false;
+    fetch(`${import.meta.env.BASE_URL}changelog.md`)
+      .then((res) => {
+        if (!res.ok) throw new Error(`HTTP ${res.status}`);
+        return res.text();
+      })
+      .then((text) => {
+        if (cancelled) return;
+        const m = text.match(/^##\s+(v[^\s#]+)\s*$/m);
+        if (m) setChangelogVersion(m[1]);
+      })
+      .catch(() => {
+        /* 静默：入口不显示版本号 */
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
   const homeText = useMemo((): HomeLocale => {
     if (!deviceState) return {} as HomeLocale;
     const loc =
@@ -956,18 +978,10 @@ export default function Home() {
             thumbnail={`${import.meta.env.BASE_URL}images/vu/vu${(ds.vu ?? 0) + 1}.png`}
             onClick={() => setLocation("/vu")}
           />
-          <ListRow
-            icon={<Undo2 size={18} />}
-            label={homeText.backToLegacy ?? "返回旧版"}
-            onClick={() => {
-              const target = ip.trim();
-              if (!target) return;
-              window.location.href = `https://am.luxsinaudio.com/i.html?ip=${encodeURIComponent(target)}`;
-            }}
-          />
           <ListRow
             icon={<BookOpenCheck size={18} />}
             label={homeText.changelog ?? "更新说明"}
+            value={changelogVersion ?? undefined}
             onClick={() => setLocation("/changelog")}
           />
         </div>