ci: skip Electron binary download in test workflow

The test job ran npm install, which triggered Electron's postinstall
binary download (~100MB) from its CDN. That download is never used by
build or test (only examples/electron uses Electron) and intermittently
fails with CDN timeouts (e.g. 504 Gateway Time-out), breaking CI.

Set ELECTRON_SKIP_BINARY_DOWNLOAD=1 so the npm package still installs
but skips the unused binary download. Faster, more reliable CI.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: KilledByAPixel

.github/workflows/test.yml

@@ -13,5 +13,9 @@ jobs:
         with:
           node-version: '22'
       - run: npm install
+        env:
+          # Engine build/test never use Electron (only examples/electron does),
+          # so skip its large binary download to avoid flaky CDN timeouts.
+          ELECTRON_SKIP_BINARY_DOWNLOAD: '1'
       - run: npm run build
       - run: npm test