feat: Hide installation identifier (#11722)

<img width="1779" alt="Screenshot 2025-06-12 at 7 21 59 PM"
src="https://github.com/user-attachments/assets/a4c54d7f-4f5f-4d72-a81b-be4d88066549"
/>




## Summary
- Hides installation identifier by default so that users don't
accidentally expose it in screenshots.

app/assets/stylesheets/administrate/components/_cells.scss

@@ -46,17 +46,25 @@
 
 .cell-data__secret-field {
   align-items: center;
+  color: $hint-grey;
   display: flex;
 
   span {
-    flex: 1;
+    flex: 0 0 auto;
   }
 
-  button {
-    margin-left: 5px;
+  [data-secret-toggler],
+  [data-secret-copier] {
+    background: transparent;
+    border: 0;
+    color: inherit;
+    margin-left: 0.5rem;
+    padding: 0;
 
     svg {
       fill: currentColor;
+      height: 1.25rem;
+      width: 1.25rem;
     }
   }
 }