fix(cli): wire initialModel/initialProvider through useSocket, add error handling

- Pass initialModel/initialProvider from CLI flags into useSocket hook
- Include provider/modelId in socket message emit (restores PR #144 functionality)
- Add provider/modelId optional fields to ChatMessagePayload type
- Add .catch() to floating promises in createConversation/deleteConversation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/types/src/chat/events.ts

@@ -62,6 +62,8 @@ export interface ErrorPayload {
 export interface ChatMessagePayload {
   conversationId?: string;
   content: string;
+  provider?: string;
+  modelId?: string;
 }
 
 /** Session info pushed when session is created or model changes */