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/distributed/coordinator.ts

@@ -3,9 +3,9 @@
  * Provides leader election, consensus, and coordination for distributed instances
  */
 
-import { EventEmitter } from 'events'
+import { EventEmitter } from 'node:events'
 import { NetworkTransport, NetworkMessage } from './networkTransport.js'
-import { createHash } from 'crypto'
+import { createHash } from 'node:crypto'
 
 export interface NodeInfo {
   id: string