Add margins and fix column widths in GTK GUI

[TheZupZup]

Overview

The GTK GUI (main.py) has no explicit margins or padding on its containers, and the TreeView columns have no minimum widths set. On a default window size, content can appear cramped or truncated.

What needs to be done

• Add set_border_width(8) (or equivalent margin_* properties) to the main Gtk.Box container in main.py
• Add explicit min_width values to TreeView columns — suggested widths:
  • Process: 140px minimum
  • PID: 60px minimum
  • Remote IP: 130px minimum
  • Port: 60px minimum
  • Status: 100px minimum
  • Trust: 90px minimum
• Add a small margin between the button row and the TreeView
• Test the result at 900x600 window size to confirm no content is cut off by default

Goal

The GUI looks clean and readable at a normal window size without the user needing to manually resize columns.

Notes

Column widths can be set with column.set_min_width(n) and column.set_resizable(True) so users can still adjust them.