feat(website): 官网多页面 + 中英文切换 + Kimi 风格科技风重设计

- 多页路由：首页 / 功能 / 更新日志 / 下载（HashRouter，适配 GitHub Pages）
- 中英文切换（zh/en 双语文案 + localStorage 记忆）
- Kimi 品牌配色（中性灰 + 蓝）+ 科技风（网格底纹 / 辉光按钮 / 渐变强调词）
- 更新日志页：运行时同步 GitHub Releases，localStorage 缓存 1h，网络失败回退内置列表
- 功能页 8 张截图卡片；下载页含自动更新说明
- 修复资源路径 404（asset() + %BASE_URL%）；自托管 Inter/Fira Code 字体

website/src/components/Nav.tsx

@@ -0,0 +1,68 @@
+import { NavLink } from "react-router-dom";
+import { useLang } from "../i18n";
+import { asset } from "../lib/asset";
+
+export default function Nav() {
+  const { lang, setLang, t } = useLang();
+  const links = [
+    { to: "/", label: t.nav.home, end: true },
+    { to: "/features", label: t.nav.features },
+    { to: "/changelog", label: t.nav.changelog },
+    { to: "/download", label: t.nav.download },
+  ];
+  return (
+    <header className="sticky top-0 z-40 border-b border-border bg-background/80 backdrop-blur">
+      <div className="container-page flex h-14 items-center justify-between gap-4">
+        <NavLink
+          to="/"
+          className="flex shrink-0 items-center gap-2 text-sm font-semibold tracking-tight"
+        >
+          <img
+            src={asset("kimi.svg")}
+            alt="Kimi Switch logo"
+            className="h-7 w-7 rounded-lg"
+          />
+          <span>Kimi Switch</span>
+        </NavLink>
+        <nav className="flex items-center gap-5 overflow-x-auto overflow-y-hidden text-sm text-muted-foreground [scrollbar-width:none] [&::-webkit-scrollbar]:hidden">
+          {links.map((l) => (
+            <NavLink
+              key={l.to}
+              to={l.to}
+              end={l.end}
+              className={({ isActive }) =>
+                `relative shrink-0 pb-1 transition-colors ${
+                  isActive ? "text-foreground" : "hover:text-foreground"
+                }`
+              }
+            >
+              {({ isActive }) => (
+                <>
+                  {l.label}
+                  <span
+                    className={`absolute -bottom-1 left-0 h-0.5 bg-primary transition-all duration-300 ${
+                      isActive ? "w-full" : "w-0"
+                    }`}
+                  />
+                </>
+              )}
+            </NavLink>
+          ))}
+        </nav>
+        <div className="flex shrink-0 items-center gap-2">
+          <button
+            type="button"
+            onClick={() => setLang(lang === "zh" ? "en" : "zh")}
+            className="rounded-lg border border-border px-2.5 py-1 text-xs font-medium text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+            aria-label="Switch language / 切换语言"
+          >
+            {lang === "zh" ? "EN" : "中文"}
+          </button>
+          <NavLink to="/download" className="btn-primary hidden text-xs sm:inline-flex md:text-sm">
+            {t.nav.downloadBtn}
+          </NavLink>
+        </div>
+      </div>
+    </header>
+  );
+}