Add DX improvements and EventEmitter support (v0.18.1)

This release introduces several developer experience improvements:

Breaking Changes:
- Add EventEmitter support - Rondevu now extends EventEmitter
- Consolidate discovery methods into findService() (getService, discoverService, discoverServices methods still exist but findService is the new unified API)

New Features:
- EventEmitter lifecycle events:
  - offer:created (offerId, serviceFqn)
  - offer:answered (offerId, peerUsername)
  - connection:opened (offerId, dataChannel)
  - connection:closed (offerId)
  - ice:candidate:local (offerId, candidate) - locally generated ICE
  - ice:candidate:remote (offerId, candidate, role) - remote ICE from server
  - error (error, context)

- Unified findService() method with modes:
  - 'direct' - direct lookup by FQN with username
  - 'random' - random discovery without username
  - 'paginated' - paginated results with limit/offset

- Typed error classes for better error handling:
  - RondevuError (base class with context)
  - NetworkError (network/API failures)
  - ValidationError (input validation)
  - ConnectionError (WebRTC connection issues)

- Convenience methods:
  - getOfferCount() - get active offer count
  - isConnected(offerId) - check connection status
  - disconnectAll() - close all connections
  - getServiceStatus() - get service state

Type Exports:
- Export ActiveOffer interface for getActiveOffers() typing
- Export FindServiceOptions, ServiceResult, PaginatedServiceResult
- Export all error classes

Dependencies:
- Add @types/node for EventEmitter support

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

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

package.json

@@ -25,6 +25,7 @@
   "license": "MIT",
   "devDependencies": {
     "@eslint/js": "^9.39.1",
+    "@types/node": "^25.0.2",
     "@typescript-eslint/eslint-plugin": "^8.48.1",
     "@typescript-eslint/parser": "^8.48.1",
     "eslint": "^9.39.1",