Implement file sending

frontend/src/core/types.d.ts

@@ -60,6 +60,7 @@ export interface Message {
     timestamp: string;
     profile_picture?: string;
     reply_to?: Message;
+    files?: Attachment[];
 }
 
 /**
@@ -230,6 +231,14 @@ export interface WebSocketCredentials {
     credentials: string;
 }
 
+export interface Attachment {
+    path: string;
+    encrypted: boolean;
+    filename?: string;
+    content_type?: string;
+    size?: number;
+}
+
 // -----------
 // React types
 // -----------