UX: fix PM user input spacing (#110)

Before:


![image](https://github.com/user-attachments/assets/3327adce-b26e-4644-82fe-d4f9611ad8e0)

After:


![image](https://github.com/user-attachments/assets/33f6a819-fa34-40f1-98de-469ab0f161f0)

scss/composer.scss

@@ -21,6 +21,7 @@
       background: var(--tertiary-low);
     }
 
+    .user-selector,
     .title-and-category {
       padding: 0 var(--spacing-inline-m);
       width: calc(100% - var(--spacing-inline-m) * 2);