v0.2.1 - improved error handling and test coverage

- add proper JSON config validation with friendly error messages
- log skipped files instead of silent continue
- refactor into smaller functions with pathlib
- add diff output for dry-run mode
- add comprehensive test suite (23 tests)
- fix CI workflow permissions
- expand README with troubleshooting section
- add CONTRIBUTING.md

v0.2.0 - improved error handling and test coverage

- add 5 more edge case tests (23 total)
- add permissions to CI workflow
- bump version to 0.2.0

Update landing page branding to textswap

- Rename from ReplaceText to textswap
- Update install command to pip install textswap
- Update Python version badge to 3.9+
- Update terminal examples with new CLI usage

add ignore directories and prefixes