ci: pin Node.js to v22 to avoid isolated-vm incompatibility

Node.js `v24` became LTS recently, causing CI failures due to `V8` API
incompatibilities with isolated-vm `v5.x`. Pinning to `v22` aligns with our
production environment (Alpine `v3.22.1` ships Node.js `v22.16.0`) and ensures
build stability.

`isolated-vm v6+` will be required for Node.js `v24` support and will be
addressed in a future dependency update cycle.

.github/workflows/tests.yml

@@ -13,7 +13,10 @@ jobs:
 
     strategy:
       matrix:
-        node-version: ["lts/*"]
+        # Pinned to Node.js 22 to maintain compatibility with isolated-vm v5.x
+        # Node.js 24 requires isolated-vm v6+ due to V8 API changes
+        # TODO: Upgrade to isolated-vm v6 and support Node.js 24 in future dependency update cycle
+        node-version: ["22"]
 
     steps:
       - name: Checkout