feat: add universal adapters for browser compatibility

- Create universal adapters for cross-platform support (browser/Node/serverless)
- Replace Node.js-specific imports with universal implementations
- Add OPFS support for browser persistent storage
- Maintain same BrainyData interface across all environments
- Enable real Brainy usage in browser console UI
- Keep package size optimized (no bloat)

Universal adapters in /src/universal/:
- uuid.ts: Cross-platform UUID generation
- crypto.ts: Browser/Node crypto operations
- fs.ts: OPFS/FileSystem/Memory storage adapter
- path.ts: Universal path operations
- events.ts: EventEmitter compatibility layer

This enables 'write once, run anywhere' for Brainy while maintaining
the exact same API. No breaking changes to existing code.

src/universal/index.ts

@@ -0,0 +1,28 @@
+/**
+ * Universal adapters for cross-environment compatibility
+ * Provides consistent APIs across Browser, Node.js, and Serverless environments
+ */
+
+// UUID adapter
+export * from './uuid.js'
+export { default as uuid } from './uuid.js'
+
+// Crypto adapter  
+export * from './crypto.js'
+export { default as crypto } from './crypto.js'
+
+// File system adapter
+export * from './fs.js'
+export { default as fs } from './fs.js'
+
+// Path adapter
+export * from './path.js'
+export { default as path } from './path.js'
+
+// Events adapter
+export * from './events.js'
+export { default as events } from './events.js'
+
+// Convenience re-exports for common patterns
+export { v4 as uuidv4 } from './uuid.js'
+export { EventEmitter } from './events.js'