Add comprehensive documentation for the `bd setup` command:
- New docs/SETUP.md with full documentation for all three integrations:
- Claude Code (hooks for SessionStart/PreCompact)
- Cursor IDE (rules file in .cursor/rules/)
- Aider (config file with human-in-the-loop workflow)
- Updated docs/CLI_REFERENCE.md:
- Added Setup & Integration section
- Added SETUP.md to See Also links
- Added to Quick Navigation
Closes#518🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>