Make Codecov failures non-blocking in CI workflow

Change fail_ci_if_error from true to false to prevent Codecov upload issues from failing the entire CI build. This is a more resilient configuration that:

- Still uploads code coverage when Codecov service is available
- Prevents transient Codecov API issues from blocking builds
- Allows builds to succeed on forks/branches without Codecov token access

The build and tests are what matter most for CI success; code coverage reporting is supplementary.

Author: claude

.github/workflows/ci.yml

@@ -52,7 +52,7 @@ jobs:
       - uses: codecov/codecov-action@v4
         with:
           name: unittests-${{ matrix.os }}
-          fail_ci_if_error: true
+          fail_ci_if_error: false
           token: ${{ secrets.CODECOV_TOKEN }}
   release:
     if: ${{ github.event.inputs.release }}