Upload frontend coverage to codecov

.github/workflows/ci.yml

@@ -211,6 +211,15 @@ jobs:
         with:
           name: jest-coverage-report
           path: src-ui/coverage
+      -
+        name: Upload frontend coverage to Codecov
+        if: always()
+        uses: codecov/codecov-action@v3
+        with:
+          # not required for public repos, but intermittently fails otherwise
+          token: ${{ secrets.CODECOV_TOKEN }}
+          # future expansion
+          flags: frontend
       -
         name: Run Playwright e2e tests
         run: cd src-ui && npx playwright test