fix: generate app-update.yml instead of copying from arch build

The arch-specific builds use --publish never, so electron-builder never
creates app-update.yml. Generate the file directly from the publish
config instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: nunocoracao

.github/workflows/release.yml

@@ -216,8 +216,8 @@ jobs:
             }).then(() => console.log('Universal merge complete'))
               .catch(err => { console.error('Universal merge failed:', err.message); process.exit(1); });
           "
-          # Copy app-update.yml that @electron/universal drops during merge
-          cp dist/mac-arm64/Watchfire.app/Contents/Resources/app-update.yml dist/mac-universal/Watchfire.app/Contents/Resources/app-update.yml
+          # Generate app-update.yml for electron-updater (not created by --publish never)
+          printf 'provider: github\nowner: watchfire-io\nrepo: watchfire\nreleaseType: release\n' > dist/mac-universal/Watchfire.app/Contents/Resources/app-update.yml
           # Sign the universal app using @electron/osx-sign (handles nested frameworks/helpers properly)
           # and notarize using @electron/notarize, then package into DMG/zip without re-signing
           node -e "