Play Framework

ci: upload tests-results/ artifact on test failure

junitlauncher's legacy-plain listener writes per-test .txt files under
framework/tests-results/ with the full failure message and stack trace.
The workflow previously discarded them, leaving only the summary line
"Tests run: N, Failures: 1" in the console log — which doesn't say
which test or why. Uploading on `if: failure()` gives us the diagnostic
trail next time CI breaks.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>