feat: Implement conversation mute and favorite features with UI, API, and state management.

src/types/messaging.ts

@@ -30,6 +30,10 @@ export interface Conversation {
   userUnreadCount: number;
   agentUnreadCount: number;
   unreadCount: number;
+  userMuted: boolean;
+  agentMuted: boolean;
+  userFavorited: boolean;
+  agentFavorited: boolean;
   createdAt: string;
   updatedAt: string;
   otherParty: OtherParty;