Cache build output and skip builds where unused

The prepare scripts (tsc --build and webpack) are most of the install time in every job, so their output is cached between runs. tsc's tsbuildinfo tracks file hashes and webpack's filesystem cache keeps its node_modules modules, so a restored cache makes both incremental.

The lint and build-mod jobs never read the compiled output: eslint is not type-aware here and build_mod.js is plain JavaScript. They now install with --ignore-scripts.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.github/workflows/node.js.yml

@@ -96,6 +96,7 @@ jobs:
     - uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ env.NODE_VERSION }}
+        ignore-scripts: true
     - run: pnpm run lint
 
   build:
@@ -106,6 +107,7 @@ jobs:
     - uses: ./.github/actions/pnpm-install
       with:
         node-version: ${{ env.NODE_VERSION }}
+        ignore-scripts: true
     - run: pnpm run build-mod
     # Upload build to artifacts
     - name: Upload build to artifacts