Add type-safe EventBus with generic event mapping

Implemented EventBus class with full TypeScript type inference:
- Generic type parameter TEvents for event name to payload mapping
- Type-safe on/once/off/emit methods with inferred data types
- Utility methods: clear, listenerCount, eventNames
- Complete JSDoc documentation with usage examples

Added core connection types:
- ConnectionIdentity, ConnectionState, ConnectionInterface
- QueueMessageOptions for message queuing
- Connection composite type

All types and classes exported from main index.

Example usage:
```typescript
interface MyEvents {
  'user:connected': { userId: string; timestamp: number };
  'message:received': string;
}

const bus = new EventBus<MyEvents>();

// TypeScript knows data is { userId: string; timestamp: number }
bus.on('user:connected', (data) => {
  console.log(data.userId, data.timestamp);
});
```

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/types.ts

@@ -0,0 +1,24 @@
+/**
+ * Core connection types
+ */
+
+export interface ConnectionIdentity {
+    id: string;
+    hostUsername: string;
+}
+
+export interface ConnectionState {
+    state: 'connected' | 'disconnected' | 'connecting';
+    lastActive: number;
+}
+
+export interface QueueMessageOptions {
+    expiresAt?: number;
+}
+
+export interface ConnectionInterface {
+    queueMessage(message: string | ArrayBuffer, options?: QueueMessageOptions): void;
+    sendMessage(message: string | ArrayBuffer): void;
+}
+
+export type Connection = ConnectionIdentity & ConnectionState & ConnectionInterface;