Add suckless coding style reference to CLAUDE.md

Rebind reading mode to Super+Q, add directional tagmondir, enable selfrestart

- Super+Q: reading mode (RRR, 3 vertical panes)
- Super+Shift+Q: killclient (close window)
- Super+Arrow: send focused window to monitor in that direction
- Remove Super+Shift+Comma/Period tagmon bindings
- Remove Super+Shift+R reading mode binding
- Enable SELFRESTART_PATCH for in-place dwm reload
- Add .claude/CLAUDE.md with development rules