chore: Simplify frontend CI workflow by removing clover.xml coverage check

### Summary of Changes
- Removed the check for `clover.xml` in the CI workflow to streamline coverage reporting.
- Updated Vitest configuration to exclude `clover` from the coverage reporters and added options for relative paths and cleaning.

### Expected Results
- Enhanced clarity and efficiency of the CI process by focusing on relevant coverage reports, improving overall workflow performance.

.gitea/workflows/frontend.yml

@@ -82,11 +82,6 @@ jobs:
         else
           echo "✗ lcov.info missing"
         fi
-        if [ -f "coverage/clover.xml" ]; then
-          echo "✓ clover.xml found"
-        else
-          echo "✗ clover.xml missing"
-        fi
         
     - name: Send results to SonarQube
       run: |
@@ -106,8 +101,7 @@ jobs:
           -Dsonar.sources.exclusions=**/*.test.js,**/*.test.jsx,**/*.spec.js,**/*.spec.jsx,src/index.js,src/setupTests.js \
           -Dsonar.tests.inclusions=**/*.test.js,**/*.test.jsx,**/*.spec.js,**/*.spec.jsx \
           -Dsonar.coverage.exclusions=**/*.test.js,**/*.test.jsx,**/*.spec.js,**/*.spec.jsx,src/index.js,src/setupTests.js \
-          -Dsonar.javascript.lcov.reportPaths=coverage/lcov.info \
-          -Dsonar.coverageReportPaths=coverage/clover.xml
+          -Dsonar.javascript.lcov.reportPaths=coverage/lcov.info
         
     - name: Test results summary
       if: always()