- Introduce SystemMonitor struct and typedef in dwn.h, add sysmon pointer to Monitor struct
- Include sysmon.h in main.c, integrate sysmon_find_by_window and sysmon_set_client into map request handling
- Add sysmon_render call in expose handler and sysmon_handle_event in button press and motion notify handlers
- Implement clickable stats and top process areas in bottom panel to toggle system monitor via sysmon_toggle
- Update build/main.d dependency file to include sysmon.h