Convert Process Lists to Sortable Tables

[Technical-1]

Priority: Medium
Labels: ui, enhancement

Description:
Convert process lists to egui::Table widgets. Make columns sortable by clicking headers. Add columns for PID, CPU%, Memory, etc.

Files to modify:

• src/main.rs

Acceptance criteria:

• Process lists converted to tables
• Columns sortable by clicking headers
• Columns for PID, Name, CPU%, Memory added
• Sort state persists during refresh
• Table is performant with many processes

Implementation notes:

• Use egui::Table widget
• Add clickable column headers
• Store sort state (column and direction) in RustDashboardApp
• Sort processes based on selected column
• Consider pagination if process list is very long