Fix coverage job - build from scratch instead of reusing artifacts

Remove dependencies on build:default since make clean wipes them anyway.
Build test-coverage independently in coverage stage.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: claude

.gitlab-ci.yml

@@ -187,8 +187,6 @@ analyze:cppcheck:
 coverage:generate:
   stage: coverage
   image: ubuntu:24.04
-  dependencies:
-    - build:default
   before_script:
     - apt-get update -qq
     - apt-get install -y -qq build-essential clang llvm llvm-tools
@@ -198,7 +196,6 @@ coverage:generate:
     - llvm-cov gcov -r build/*-coverage.gcno
     - mkdir -p coverage_report
     - find build -name "*.gcov" -exec cp {} coverage_report/ \;
-    - ls -lah coverage_report/
   artifacts:
     paths:
       - coverage_report/