feat: v0.9.0 - durable WebRTC connections with automatic reconnection

Major refactor replacing low-level APIs with high-level durable connections.

New Features:
- Automatic reconnection with exponential backoff (1s → 2s → 4s → ... max 30s)
- Message queuing during disconnections
- Durable channels that survive connection drops
- TTL auto-refresh for services (refreshes at 80% of TTL by default)
- Full configuration of timeouts, retry limits, and queue sizes

New API:
- client.exposeService() - Create durable service with automatic TTL refresh
- client.connect() - Create durable connection with automatic reconnection
- client.connectByUuid() - Connect by service UUID
- DurableChannel - Event-based channel wrapper with message queuing
- DurableConnection - Connection manager with reconnection logic
- DurableService - Service manager with TTL auto-refresh

Files Added:
- src/durable/types.ts - Type definitions and enums
- src/durable/reconnection.ts - Exponential backoff utilities
- src/durable/channel.ts - DurableChannel class (358 lines)
- src/durable/connection.ts - DurableConnection class (441 lines)
- src/durable/service.ts - DurableService class (329 lines)
- MIGRATION.md - Comprehensive migration guide

Files Removed:
- src/services.ts - Replaced by DurableService
- src/discovery.ts - Replaced by DurableConnection

BREAKING CHANGES:
- Removed: client.services.*, client.discovery.*, client.createPeer()
- Added: client.exposeService(), client.connect(), client.connectByUuid()
- Handler signature: (channel, peer, connectionId?) → (channel, connectionId)
- Event handlers: .onmessage → .on('message')
- Services: Must call service.start() to begin accepting connections
- Connections: Must call connection.connect() to establish connection

src/index.ts

@@ -1,6 +1,6 @@
 /**
  * @xtr-dev/rondevu-client
- * WebRTC peer signaling and discovery client with topic-based discovery
+ * WebRTC peer signaling and discovery client with durable connections
  */
 
 // Export main client class
@@ -11,44 +11,26 @@ export type { RondevuOptions } from './rondevu.js';
 export { RondevuAuth } from './auth.js';
 export type { Credentials, FetchFunction } from './auth.js';
 
-// Export offers API
-export { RondevuOffers } from './offers.js';
-export type {
-  CreateOfferRequest,
-  Offer,
-  IceCandidate,
-  TopicInfo
-} from './offers.js';
-
-// Export peer manager
-export { default as RondevuPeer } from './peer/index.js';
-export type {
-  PeerOptions,
-  PeerEvents,
-  PeerTimeouts
-} from './peer/index.js';
-
 // Export username API
 export { RondevuUsername } from './usernames.js';
 export type { UsernameClaimResult, UsernameCheckResult } from './usernames.js';
 
-// Export services API
-export { RondevuServices } from './services.js';
-export type {
-  ServicePublishResult,
-  PublishServiceOptions,
-  ServiceHandle
-} from './services.js';
+// Export durable connection APIs
+export { DurableConnection } from './durable/connection.js';
+export { DurableChannel } from './durable/channel.js';
+export { DurableService } from './durable/service.js';
 
-// Export discovery API
-export { RondevuDiscovery } from './discovery.js';
+// Export durable connection types
 export type {
-  ServiceInfo,
-  ServiceListResult,
-  ServiceQueryResult,
-  ServiceDetails,
-  ConnectResult
-} from './discovery.js';
-
-// Export pool types
-export type { PoolStatus, PooledServiceHandle } from './service-pool.js';
+  DurableConnectionState,
+  DurableChannelState,
+  DurableConnectionConfig,
+  DurableChannelConfig,
+  DurableServiceConfig,
+  QueuedMessage,
+  DurableConnectionEvents,
+  DurableChannelEvents,
+  DurableServiceEvents,
+  ConnectionInfo,
+  ServiceInfo
+} from './durable/types.js';