fix: solve small pm chat ui issues

unwrap the pill
fix the fetching images in pm not auto download

toju-app/src/app/shared-kernel/message.models.ts

@@ -17,6 +17,8 @@ export interface Message {
   senderName: string;
   content: string;
   timestamp: number;
+  kind?: 'user' | 'system';
+  systemEvent?: 'call-started';
   editedAt?: number;
   reactions: Reaction[];
   isDeleted: boolean;