Frontend: use github-versions.json for version display (#11281)

* fix(frontend): use github-versions.json for version display

- Update AppVersion type to match new format with slug field
- Switch from versions.json to github-versions.json API
- Simplify version matching by direct slug comparison
- Remove 'Loading versions...' text - show nothing if no version found

* feat(frontend): show tooltip for pinned versions

* fix(api): add github-versions endpoint and fix legacy versions route

frontend/src/app/api/github-versions/route.ts

@@ -0,0 +1,36 @@
+import { NextResponse } from "next/server";
+import { promises as fs } from "node:fs";
+import path from "node:path";
+
+import type { GitHubVersionsResponse } from "@/lib/types";
+
+export const dynamic = "force-static";
+
+const jsonDir = "public/json";
+const versionsFileName = "github-versions.json";
+const encoding = "utf-8";
+
+async function getVersions(): Promise<GitHubVersionsResponse> {
+  const filePath = path.resolve(jsonDir, versionsFileName);
+  const fileContent = await fs.readFile(filePath, encoding);
+  const data: GitHubVersionsResponse = JSON.parse(fileContent);
+  return data;
+}
+
+export async function GET() {
+  try {
+    const versions = await getVersions();
+    return NextResponse.json(versions);
+  }
+  catch (error) {
+    console.error(error);
+    const err = error as globalThis.Error;
+    return NextResponse.json({
+      generated: "",
+      versions: [],
+      error: err.message || "An unexpected error occurred",
+    }, {
+      status: 500,
+    });
+  }
+}