Add Mermaid diagram support

- Install astro-mermaid and mermaid packages
- Configure mermaid integration in astro.config.mjs
- Enables rendering of Mermaid diagrams in MDX files

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: groksrc

astro.config.mjs

@@ -4,10 +4,11 @@ import { defineConfig } from 'astro/config';
 import mdx from '@astrojs/mdx';
 import react from '@astrojs/react';
 import pagefind from 'astro-pagefind';
+import mermaid from 'astro-mermaid';
 
 // https://astro.build/config
 export default defineConfig({
-  integrations: [mdx(), react(), pagefind()],
+  integrations: [mdx(), react(), pagefind(), mermaid()],
   markdown: {
     syntaxHighlight: 'shiki',
     shikiConfig: {