fix: Update lcov command to ignore unused files in coverage report

Author: VPRamon

.github/workflows/ci.yml

@@ -118,7 +118,7 @@ jobs:
           lcov --capture --directory build --output-file coverage.info --ignore-errors mismatch
           # Exclude system, tests, and only the top-level Rust workspace folder.
           # Do NOT exclude include/qtty (our C++ headers), which caused empty reports.
-          lcov --remove coverage.info '/usr/*' '*/tests/*' '*/build/*' "${GITHUB_WORKSPACE}/qtty/*" --output-file coverage.info --ignore-errors empty
+          lcov --remove coverage.info '/usr/*' '*/tests/*' '*/build/*' "${GITHUB_WORKSPACE}/qtty/*" --output-file coverage.info --ignore-errors empty,unused
           lcov --list coverage.info
 
       - name: Generate HTML coverage report