feat: add formatted output for Claude Code execution reports (#18)

* feat: add formatted output for Claude Code execution reports

- Write turns formatter
- Modify GitHub Action to call formatter instead of dumping raw JSON
- Add comprehensive unit tests (30 tests) covering all functionality
- Add integration test with sample data for output consistency
- Support syntax highlighting for multiple content types (JSON, Python, bash, etc.)
- Include turn grouping logic and token usage tracking
- Provide CLI interface for standalone formatter usage

🤖 Generated with [Claude Code](https://claude.ai/code)
Note: seriously I have never written any line of ts code in my life, so
please make sure this is fine as I don't give any guarantees

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

* Add fallback

---------

Co-authored-by: Claude <noreply@anthropic.com>

.prettierignore

@@ -0,0 +1,2 @@
+# Test fixtures should not be formatted to preserve exact output matching
+test/fixtures/