Warn about unsaved QA Validation Runner changes on client exit

If the QA Validation Runner panel (QaValidationRunnerWidget, in ores.qt/api) has step results or notes ticked/entered but not yet written back to the test_scenario doc's * Results=/=*** Result sections, and the user tries to close the Qt client (whole-app quit, not just the panel), warn them with a dialog offering to save first – the same "unsaved changes" guard every other editable dialog/window in the app already gives before a destructive action, rather than silently discarding the run. Track a dirty flag on the widget (set whenever a step's status/notes change, cleared on save) and check it in the application's close/quit path, prompting Save/Discard/Cancel like a standard "unsaved changes" dialog.

Surfaced during manual QA of Badge palette swatch rendering + data-driven fallback badge: the tester ran through every step of a fallback-badge/eventing test scenario and marked them all as passed, but the client closed (or the panel was otherwise left) before the results were saved – the on-disk scenario doc still showed only the first 3 steps as PASS and the rest PENDING, with a stale "Completed at" timestamp from an earlier partial run. The statuses had to be reconstructed and re-applied by hand afterwards. A save-on-exit prompt would have caught this at the moment the client was closed, instead of leaving a silently incomplete test record that looked plausible (a "PASSED" Results header) but didn't match the per-step detail.

• projects/ores.qt/api/src/QaValidationRunnerWidget.cpp – the panel this applies to.
• Test Scenario: Verify data-driven fallback badge and badge eventing – the scenario whose lost save prompted this capture.

• Badge palette swatch rendering + data-driven fallback badge – the task being manually QA'd when this was noticed.