feat: add node: protocol to all Node.js built-in imports for bundler compatibility

- Updated all fs, path, crypto, os, url, util, events, http, https, net, child_process, stream, and zlib imports
- Changed both static imports and dynamic imports to use node: protocol
- This makes Brainy more bundler-friendly by explicitly marking Node.js built-ins
- Prevents bundlers from attempting to polyfill or bundle these modules
- Reduces bundle size for web applications using Brainy
- Improves tree-shaking and dead code elimination

Benefits for external bundlers:
- Clear distinction between Node.js built-ins and external dependencies
- No ambiguity about what needs polyfilling
- Smaller bundles for browser builds
- Better compatibility with modern bundlers (Webpack 5, Vite, Rollup, esbuild)

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

src/config/storageAutoConfig.ts

@@ -344,8 +344,8 @@ async function isWritable(dirPath: string): Promise<boolean> {
   
   try {
     // Dynamic import fs for Node.js
-    const { promises: fs } = await import('fs')
-    const path = await import('path')
+    const { promises: fs } = await import('node:fs')
+    const path = await import('node:path')
     
     // Try to create directory if it doesn't exist
     await fs.mkdir(dirPath, { recursive: true })