Make it possible to adjust the dimensions of Pika’s chat window

Add a feature to the Pika that allows users to adjust the width and height of the chat window. This feature could make the chat more user-friendly.

<img width="495" height="327" alt="Image" src="https://github.com/user-attachments/assets/f54d9eaf-368b-4fc6-87bc-aeba13bb6466" />