Add test result bundle artifact for CI diagnostics

Upload xcresult bundle on every run (pass or fail) to help debug
CI-specific failures like the ibtoold crashes.

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

Author: gnachman

.github/workflows/test.yml

@@ -28,6 +28,15 @@ jobs:
             -project iTerm2.xcodeproj \
             -scheme ModernTests \
             -parallel-testing-enabled NO \
+            -resultBundlePath TestResults.xcresult \
             CODE_SIGN_IDENTITY="" \
             CODE_SIGNING_REQUIRED=NO \
             CODE_SIGNING_ALLOWED=NO
+
+      - name: Upload test results
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: test-results
+          path: TestResults.xcresult
+          retention-days: 7