Make code syntax highlighting works

[thanhnguyen2187]

Relevant code pointers:

• src/lib/card-v2.svelte: look at how we are using CodeBlock
• src/lib/modal-snippet.svelte: look at how we are using a simple textarea

[thanhnguyen2187]

The plan is to use codejar instead of CodeMirror or Monaco for the library's lightweightness.

• https://github.com/antonmedv/codejar#getting-started
• https://codemirror.net
• https://microsoft.github.io/monaco-editor/

[thanhnguyen2187]

Also, we should think about picking prism.js and highlight.js.

• https://prismjs.com
• https://highlightjs.org