RenderFlex overflow in pair_chat_dialog

### 🐛 Describe the bug

Location

lib/views/widgets/pair_chat_dialog.dart

Description

When opening the pair chat dialog, the UI overflows with this error:

RenderFlex overflowed by 99614 pixels on the bottom
Cause

The dialog content uses a Column without scroll or height constraints, so it exceeds screen height.

Fix

Wrap the content with SingleChildScrollView and add a height constraint to prevent overflow.