Restrict fpm-deployment coverage upload to the filtered src/ report

[Copilot]

The fpm_deployment coverage job was correctly generating an lcov report filtered to src/, but the Codecov upload step was still auto-discovering generated *.gcov files under example/. That allowed example/ to be treated as the analyzed source path instead of keeping coverage anchored to src/.

• Root cause

  • The workflow filtered coverage data down to src/ during report generation.
  • The subsequent Codecov step still searched the workspace for additional coverage artifacts and picked up generated files from example/ / test/.

• Change

  • Disable Codecov's automatic coverage file search in fpm-deployment.
  • Upload only the explicit filtered report: build/coverage/coverage.info.

• Resulting behavior

  • src/ remains the effective source root for coverage analysis.
  • example/ is no longer eligible to override or pollute source resolution during upload.
  • Build/test behavior in the workflow remains unchanged.

• Workflow note

  • Added an inline comment documenting why the upload must be restricted to the filtered lcov artifact.

- name: Upload coverage report
  uses: codecov/codecov-action@v4
  with:
    token: ${{ secrets.CODECOV_TOKEN }}
    disable_search: true
    files: build/coverage/coverage.info