fix(pwa): rename serwist route from [[...slug]] to [path] to match Serwist's hardcoded param

The Serwist createSerwistRoute factory returns a GET handler with
`params: Promise<{ path: string }>` hardcoded. Next.js infers the
param shape from the directory name — so the directory MUST be
named `[path]` (single segment) for the type to match.

`[[...slug]]` (catch-all) was wrong on two counts:
1. The segment name is `slug`, not `path` (Serwist expects
   exactly `path`).
2. The shape is `string[]` (array), not `string` (Serwist
   expects a single string).

Per the Serwist source comment: 'Asset and chunk names must be at
the top, as our path is /serwist/[path], not /serwist/[...path]'
— all SW output files (sw.js, workbox-XXX.js) are flat, single
segment is sufficient.

The fix is a directory rename only — the route.ts content
(createSerwistRoute call) is unchanged.

Verification:
- pnpm build now succeeds (TypeScript check passes)
- The Serwist route appears in the build output as `●  /serwist/[path]`
  prerendered with `sw.js` and `sw.js.map` static pages
- `pnpm start` + Chrome: `/serwist/sw.js` will be served by the
  route handler and registered by <SerwistProvider>

src/app/serwist/[path]/route.ts

@@ -0,0 +1,26 @@
+import { spawnSync } from "node:child_process";
+import { createSerwistRoute } from "@serwist/turbopack";
+
+/**
+ * Cozsweet Serwist Service Worker Route Handler
+ *
+ * 路径：捕获 `/serwist/*` 所有子路径（典型是 `/serwist/sw.js` 主 SW + 一些 Serwist 内部 chunk）
+ * 因此 `[[...slug]]` 是必须的 —— 仅 `app/serwist/sw.js` 一条不够，Serwist 还会
+ * 拉取 `/serwist/<chunk>.js` 等辅助资源。
+ *
+ * `createSerwistRoute` 在 build 阶段用 esbuild 把 `src/app/sw.ts` 编译成真实 SW，
+ * 并在 runtime 把编译产物通过 GET handler 吐出去。
+ *
+ * Revision 用 `git rev-parse HEAD` —— 每次 commit 变化让 precache 失效，强制客户端
+ * 拉新 SW。fallback 到 randomUUID（罕见的非 git 环境兜底）。
+ */
+const revision =
+  spawnSync("git", ["rev-parse", "HEAD"], { encoding: "utf-8" }).stdout ??
+  crypto.randomUUID();
+
+export const { dynamic, dynamicParams, revalidate, generateStaticParams, GET } =
+  createSerwistRoute({
+    additionalPrecacheEntries: [{ url: "/~offline", revision }],
+    swSrc: "src/app/sw.ts",
+    useNativeEsbuild: true,
+  });