- Add process 'error' event handler to catch spawn failures (e.g., yt-dlp not installed)
- Separate stdout/stderr to prevent yt-dlp warnings from corrupting parsed output
- Add try-catch for RegExp construction from YTDLP_SANITIZE_ILLEGAL_CHARS env var
- Add NaN validation for YTDLP_MAX_FILENAME_LENGTH env var
- Sync VERSION constant with package.json (0.8.4)
- Update tests for new output format and null handling
- Add version sync guidance to CLAUDE.md
- Add .claude/ directory and CLAUDE.md to .gitignore
- Add development guideline to always update CHANGELOG.md
- Update CHANGELOG.md with unreleased changes
