feat(website): serve paseo.sh in Simplified Chinese

Every page of the website now has a Simplified Chinese version under
/zh-CN: the interface, docs, blog posts, comparison pages, legal pages,
all changelog releases and the homepage mockup. English URLs are unchanged.

The URL alone decides the language. There is no browser-language redirect
and no stored preference, because either would have to redirect the
unprefixed English URLs that people share and search engines index.
Internal links carry the page's language instead, and hreflang alternates
point Chinese search results at /zh-CN.

Translated headings pin the English anchor with {#id}, so section links
work in both languages. content-translations.test.ts fails when a page
has no translation or a translation's headings drift from the English.
Changelog releases and plugin listings without a translation render
whole in English under a notice, so a release never waits on one.

Plugin manifests and the registry gain optional translations and
OVERVIEW.zh-CN.md fields; older clients and registries ignore them.

packages/cli/src/commands/plugin/scaffold.test.ts

@@ -55,18 +55,19 @@ describe("plugin scaffold", () => {
     expect(await readdir(directory)).toContain("paseo-plugin.json");
   });
 
-  it("includes the author overview in the packed npm artifact", async () => {
+  it("includes the author overview and its translations in the packed npm artifact", async () => {
     const parent = await mkdtemp(path.join(tmpdir(), "paseo-plugin-scaffold-"));
     directories.push(parent);
     const directory = path.join(parent, "packed-plugin");
     await scaffoldPluginDirectory(directory);
+    await writeFile(path.join(directory, "OVERVIEW.zh-CN.md"), "插件概览\n");
 
     const { stdout } = await execAsync("npm pack --dry-run --ignore-scripts --json", {
       cwd: directory,
     });
     const [artifact] = JSON.parse(stdout) as { files: { path: string }[] }[];
     expect(artifact.files.map((file) => file.path)).toEqual(
-      expect.arrayContaining(["OVERVIEW.md", "paseo-plugin.json"]),
+      expect.arrayContaining(["OVERVIEW.md", "OVERVIEW.zh-CN.md", "paseo-plugin.json"]),
     );
   });
 
@@ -105,6 +106,7 @@ describe("plugin scaffold", () => {
         files: [
           "paseo-plugin.json",
           "OVERVIEW.md",
+          "OVERVIEW.*.md",
           "index.client.ts",
           "index.client.tsx",
           "index.server.ts",

packages/cli/src/commands/plugin/scaffold.ts

@@ -28,6 +28,9 @@ when they help. Use sentence case and plain factual language, with no em dashes.
 Omit installation commands, badges, changelog, contributing or license sections,
 marketing, and unsupported claims. Avoid implementation filler such as empty
 cleanup functions, theme-token field lists, or lists of absent features.
+
+To translate the overview, add a whole copy beside this file named for the
+language, such as OVERVIEW.zh-CN.md. Readers in that language see it instead.
 -->
 `;
 
@@ -184,6 +187,7 @@ export async function scaffoldPluginDirectory(
     files: [
       "paseo-plugin.json",
       "OVERVIEW.md",
+      "OVERVIEW.*.md",
       "index.client.ts",
       "index.client.tsx",
       "index.server.ts",