fix(ci): repair github actions runners

Use the repository-installed TypeScript compiler in CI tests and restore docker/setup-buildx-action so the container workflow can use the GitHub Actions cache backend.

.github/workflows/image.yml

@@ -41,6 +41,9 @@ jobs:
         id: vars
         run: echo "image_name=ghcr.io/${GITHUB_REPOSITORY,,}" >> "$GITHUB_OUTPUT"
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Extract image metadata
         id: meta
         uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7

tests/open-source-build.test.cjs

@@ -21,15 +21,7 @@ test('default build script uses standard TypeScript compiler', () => {
 });
 
 test('project type-check build passes with tsc', () => {
-  const tscJsPath = path.join(
-    projectRoot,
-    '.codex-cache',
-    'ts-compiler',
-    'node_modules',
-    'typescript',
-    'lib',
-    'tsc.js',
-  );
+  const tscJsPath = path.join(projectRoot, 'node_modules', 'typescript', 'lib', 'tsc.js');
   const result = spawnSync(
     process.execPath,
     [tscJsPath, '-p', '.', '--pretty', 'false'],