Fix: small frontend css class fixes, remove unused component

src-ui/src/app/components/common/toast/toast.component.html

@@ -33,7 +33,7 @@
                 }
                 <div class="row">
                     <div class="col offset-sm-3">
-                    <button class="btn btn-sm btn-outline-dark" (click)="copyError(toast.error)">
+                    <button class="btn btn-sm btn-outline-secondary" (click)="copyError(toast.error)">
                         @if (!copied) {
                         <i-bs name="clipboard"></i-bs>&nbsp;
                         }