fix(macos): improve notarization with timeout and graceful failure

Changes:
- Add 30 minute timeout for notarization (fail fast)
- Add SKIP_NOTARIZE=true env var to skip notarization entirely
- Don't fail build if notarization fails (app still code-signed)
- Add NOTARIZE_FAIL_ON_ERROR=true to fail build on notarization error
- Add forceCodeSigning, strictVerify, type=distribution to mac config
- Disable electron-builder built-in notarize (using custom script)

This prevents CI from hanging forever waiting for Apple's notarization
service and reduces wasted GitHub Actions minutes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -138,7 +138,11 @@
       "hardenedRuntime": true,
       "gatekeeperAssess": false,
       "entitlements": "build/entitlements.mac.plist",
-      "entitlementsInherit": "build/entitlements.mac.plist"
+      "entitlementsInherit": "build/entitlements.mac.plist",
+      "forceCodeSigning": true,
+      "strictVerify": true,
+      "type": "distribution",
+      "notarize": false
     },
     "afterSign": "scripts/notarize.js",
     "nsis": {