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/storage/cacheManager.ts

@@ -463,7 +463,7 @@ export class CacheManager<T extends HNSWNode | Edge | HNSWVerb> {
       if (this.environment === Environment.NODE) {
         try {
           // Use dynamic import for OS module
-          const os = await import('os')
+          const os = await import('node:os')
           
           // Get actual system memory information
           const totalMemory = os.totalmem()