fix: ship verified npm panel packages and test production migrations

shell/install-package.cjs

@@ -0,0 +1,32 @@
+const fs = require('node:fs');
+const path = require('node:path');
+const { createHash, randomUUID } = require('node:crypto');
+
+function restorePackageLock(root = path.resolve(__dirname, '..')) {
+  const copy = path.join(root, 'shell/upgrade-lock.yaml');
+  const destination = path.join(root, 'pnpm-lock.yaml');
+  if (!fs.existsSync(copy)) {
+    // Source checkouts already have the canonical lock; no built artifacts yet.
+    if (fs.existsSync(destination)) return;
+    throw new Error('Missing npm package upgrade lockfile');
+  }
+  const bytes = fs.readFileSync(copy);
+  const manifest = JSON.parse(
+    fs.readFileSync(path.join(root, 'static/build-info.json'), 'utf8'),
+  );
+  if (
+    manifest.dirty !== false ||
+    manifest.lockfileSha256 !== createHash('sha256').update(bytes).digest('hex')
+  )
+    throw new Error('npm package lockfile does not match its build manifest');
+  const temporary = path.join(root, `.upgrade-lock-${randomUUID()}`);
+  try {
+    fs.writeFileSync(temporary, bytes, { flag: 'wx', mode: 0o644 });
+    fs.renameSync(temporary, destination);
+  } finally {
+    fs.rmSync(temporary, { force: true });
+  }
+}
+
+module.exports = { restorePackageLock };
+if (require.main === module) restorePackageLock();