[FEAT] mermaid diagrams visualization on ui

[adityasharma3]

Is your feature request related to a problem? Please describe.
When analyzing complex codebases or architectural flows, I frequently prompt the AI to generate Mermaid.js diagrams. Currently, the UI renders these as raw code blocks. To visualize them, I have to manually copy-paste the code into external tools (like Mermaid Live Editor), which disrupts the development workflow and adds unnecessary friction to the "understanding" phase of coding.

[matt1398]

Nice suggestion! Will look into it.