test: add web-admin build id and version.json helpers.

Co-authored-by: Cursor <cursoragent@cursor.com>

web-admin/scripts/app-build-meta.ts

@@ -0,0 +1,31 @@
+// web-admin/scripts/app-build-meta.ts
+import fs from 'node:fs'
+import path from 'node:path'
+
+export type AppBuildMeta = {
+  version: string
+  buildId: string
+}
+
+export function readGitShort(run: () => string): string {
+  try {
+    const text = run().trim()
+    return text || 'nogit'
+  } catch {
+    return 'nogit'
+  }
+}
+
+export function createAppBuildMeta(version: string, nowMs: number, gitShort: string): AppBuildMeta {
+  const hash = gitShort.trim() || 'nogit'
+  return { version, buildId: `${hash}-${nowMs}` }
+}
+
+export function versionJsonText(meta: AppBuildMeta): string {
+  return `${JSON.stringify({ version: meta.version, buildId: meta.buildId }, null, 2)}\n`
+}
+
+export function writeVersionJson(outDir: string, meta: AppBuildMeta): void {
+  fs.mkdirSync(outDir, { recursive: true })
+  fs.writeFileSync(path.join(outDir, 'version.json'), versionJsonText(meta), 'utf8')
+}