Expand user message textarea height while editing in Web UI

[nihilfacit]

Currently, the textarea used for editing a user message is about three lines tall.
In my opinion, increasing the number of displayable lines would improve the editing experience.

I've attached the code I implemented along with a demo video of its operation.
Code changes:

• Add auto‑resize feature to the textarea.
• Set the maximum height of the textarea to twice the minimum height.

master...nihilfacit:llama.cpp:feature-webui-add-auto‑resize-to-expand-user-message-textarea-height-while-editing

Screen.Recording.2025-10-23.at.13.50.26.mov

I use llama.cpp daily through the Web UI. Thank you all for your efforts.

[dwrz]

I use the UI infrequently; when I do, it's on mobile. The recent changes have negatively affected the accessibility of the UI on mobile in several ways. This is one of them and it would be great to see this change implemented.