fix: sanitize artifact names to handle special characters in matrix vars

The valgrind and sanitizer test matrix names contain parentheses and slashes
(e.g., 'Valgrind (01/10)', 'ASan/UBSan (01/12)') which are invalid in artifact
filenames. Replace these characters with hyphens to ensure reliable artifact uploads.

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

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

.github/workflows/ci.yaml

@@ -519,7 +519,7 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v4
         with:
-          name: pytest-results-integration-valgrind-${{ matrix.NAME }}
+          name: pytest-results-integration-valgrind-${{ replace(replace(replace(matrix.NAME, '/', '-'), '(', '-'), ')', '') }}
           path: report.xml
           if-no-files-found: ignore
 
@@ -596,7 +596,7 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v4
         with:
-          name: pytest-results-integration-sanitizers-${{ matrix.NAME }}
+          name: pytest-results-integration-sanitizers-${{ replace(replace(replace(matrix.NAME, '/', '-'), '(', '-'), ')', '') }}
           path: report.xml
           if-no-files-found: ignore