## ℹ️ Description
* Restrict coverage reporting to library files and collect per-suite
coverage data for Codecov’s flags.
- Link to the related issue(s): Issue #N/A
- Describe the motivation and context for this change.
## 📋 Changes Summary
- add `coverage:prepare` and per-suite `COVERAGE_FILE`s so each test
group writes its own sqlite and XML artifacts without appending
- replace the shell scripts with `scripts/coverage_helper.py`, scope the
report to `src/kleinanzeigen_bot/*`, and add logging/validation around
cleanup, pytest runs, and data combining
- ensure the helper works in CI (accepts extra pytest args, validates
file presence)
### ⚙️ Type of Change
- [x] 🐞 Bug fix (non-breaking change which fixes an issue)
- [ ] ✨ New feature (adds new functionality without breaking existing
usage)
- [ ] 💥 Breaking change (changes that might break existing user setups,
scripts, or configurations)
## ✅ Checklist
- [x] I have reviewed my changes to ensure they meet the project's
standards.
- [x] I have tested my changes and ensured that all tests pass (`pdm run
test`).
- [x] I have formatted the code (`pdm run format`).
- [x] I have verified that linting passes (`pdm run lint`).
- [x] I have updated documentation where necessary.
