server : (web ui) Various improvements, now use vite as bundler

[ngxson]

Motivation

The new web UI has received significantly more positive feedback than anticipated, prompting consideration for further enhancements.

Currently, we operate without a bundler, running code directly from index.html and 3rd party libraries from deps.sh. However, this approach has limitations, particularly with daisyui component compatibility. It also leave a big binary size with many redundant parts inside.

Given that many llama.cpp contributors have a lower-level programming background, here's a brief overview of the current UI tech stack and why we need to use them:

• Tailwindcss: A CSS framework that simplifies styling, used by major platforms like ChatGPT, Claude, and Hugging Face
• Daisyui: A tailwindcss-based component library offering ready-to-use elements like chat bubbles, buttons, and themes
• Due to the large size of these libraries (up to 2MB for pre-compiled versions), we need vite as a bundler to eliminate unused code. This also enables compilation into a single .html file, eliminating runtime dependencies.

Improvements

Key updates in this PR:

• Project relocated to server/webui using npm for dependency management (with deps.sh script removed)
• Integration of vite bundler (build instructions in server/README.md). Output index.html size is just under 500kb, which is smaller than the old approach with deps.sh (Remind: this new index.html contains everything needed)
• Enhanced mobile compatibility (screenshots below)

For binary size, this PR recudes 1MB of the final compiled binary compared to master:

# master
$ ls -lah llama-server
-rwxr-xr-x  1 ngxson  staff   5.5M Nov 30 15:02 llama-server

# PR
-rwxr-xr-x  1 ngxson  staff   4.5M Nov 30 14:52 llama-server

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