server: (UI) add syntax highlighting and latex math rendering (#10808)

* add code highlighting and math formatting

* code cleanup

* build public/index.html

* rebuild public/index.html

* fixed coding style

* fixed coding style

* style fixes

* highlight: smaller bundle size, fix light & dark theme

* remove katex

* add bundle size check

* add more languages

* add php

* reuse some langs

* use gzip

* Revert "remove katex"

This reverts commit c0e5046accd10be3f83018cffdc29a652849fc61.

* use better maintained @vscode/markdown-it-katex

* fix gzip non deterministic

* ability to add a demo conversation for dev

* fix latex rendering

* add comment

* latex codeblock as code

---------

Co-authored-by: Xuan Son Nguyen <son@huggingface.co>

examples/server/webui/index.html

@@ -201,6 +201,10 @@
           <details class="collapse collapse-arrow bg-base-200 mb-2 overflow-visible">
             <summary class="collapse-title font-bold">Advanced config</summary>
             <div class="collapse-content">
+              <div class="flex flex-row items-center mb-2" v-if="isDev">
+                <!-- this button only shows in dev mode, used to import a demo conversation to test message rendering -->
+                <button class="btn" @click="debugImportDemoConv()">(debug) Import demo conversation</button>
+              </div>
               <div class="flex flex-row items-center mb-2">
                 <input type="checkbox" class="checkbox" v-model="config.showTokensPerSecond" />
                 <span class="ml-4">Show tokens per second</span>