Fix workflows to fail on test failures

The '|| true' was swallowing test runner exit codes, causing workflows
to pass even when tests failed. Added separate 'Check test results'
step that reads JSON summary and fails workflow if any tests failed.

Affected workflows:
- build.yml
- runtime.yml
- inference.yml
- full-pipeline.yml

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.github/workflows/inference.yml

@@ -63,6 +63,15 @@ jobs:
           echo "--- JSON Results ---"
           cat /tmp/inference-results.json
 
+      - name: Check test results
+        run: |
+          FAILED=$(jq '.summary.failed' /tmp/inference-results.json)
+          echo "Failed tests: $FAILED"
+          if [ "$FAILED" -gt 0 ]; then
+            echo "::error::$FAILED inference test(s) failed"
+            exit 1
+          fi
+
       - name: Upload inference results
         uses: actions/upload-artifact@v4
         if: always()