feat: Update endpoint signup

endpoints/signup.post.py

@@ -44,7 +44,7 @@ async def signup(
 
     # Return token directly after registration
     return {
-        "message": "User created successfully",
+        "message": "User joined successfully",
         "access_token": create_access_token({"sub": new_user.id}),
         "token_type": "bearer"
     }