Add Visual Status Indicators

[Technical-1]

Priority: Low
Labels: ui, enhancement

Description:
Add visual health indicators (green/yellow/red dots) showing system load status. Display warnings for high CPU/memory usage.

Files to modify:

• src/main.rs

Acceptance criteria:

• Health indicators added (colored dots)
• System load status displayed
• Warnings shown for high CPU usage
• Warnings shown for high memory usage
• Indicators update with refresh interval

Implementation notes:

• Create helper function to determine system health status
• Use egui::CircleShape or colored text for indicators
• Display in top panel or next to relevant metrics
• Show warning messages when thresholds exceeded
• Consider using icons or emoji for visual appeal