Restructure UI Layout

[Technical-1]

Priority: Medium
Labels: ui, enhancement

Description:
Replace single scrollable panel with grid layout. Use egui::Grid for organized sections. Add side panel for navigation or settings.

Files to modify:

• src/main.rs

Acceptance criteria:

• Grid layout implemented
• Sections organized in grid
• Side panel added (optional)
• UI remains responsive
• Layout is more organized and scannable

Implementation notes:

• Replace ScrollArea with Grid layout
• Organize sections (CPU, Memory, Disk, Network, Processes) in grid
• Consider using egui::SidePanel for settings/navigation
• Maintain responsive design
• Test on different window sizes