Electron Releases

Description of Change

api-autoupdater-darwin-spec.ts is the long pole of CI: ~29 min of the slowest macOS x64 test shard (~10 min on arm64), because every test copies and deep-signs the whole app bundle a couple of times and then runs one Squirrel install cycle at a time.

• Build one stripped, deep-signed template app per run. Every fixture app and update payload is an APFS clone of it with only Info.plist / Resources/app changed, so it only needs a shallow re-sign.
• Run the "with update server" tests concurrently in a small slot pool (4 on 8+ core runners, else 2; ELECTRON_SPEC_UPDATER_CONCURRENCY overrides). Each slot gets its own CFBundleIdentifier so ShipIt's launchd job / XPC name / cache dir don't collide, and each task gets its own update server. The mocha test for each task just awaits it, so per-test reporting and retries are unchanged.
• Stacked-update tests fetch extra payloads via getUpdateZip() instead of nesting withUpdatableApp(), which built start apps nothing launched.
• SquirrelMacEnableDirectContentsWrite is set in the fixture app's own defaults domain now that it no longer shares the runner's bundle id.

First CI run on this branch (33716702873) vs recent main:

All mac shards passed first try, so the shallow re-sign holds up under Squirrel's strict validation on both arches.

Checklist

• PR description included

Release Notes

Notes: none