Replace browser confirmations with confirmation dialog

frontend/src/app/components/confirmation-dialog/confirmation-dialog.css

@@ -0,0 +1,23 @@
+:host {
+  display: block;
+}
+
+.confirmation-dialog h2 {
+  margin-bottom: 8px;
+  color: var(--text);
+  font-size: 1.25rem;
+  letter-spacing: -0.025em;
+}
+
+.confirmation-dialog p {
+  margin: 0;
+  color: var(--text-muted);
+  line-height: 1.55;
+}
+
+.confirmation-dialog .confirm-action.mat-mdc-unelevated-button {
+  --mdc-filled-button-container-color: var(--danger);
+  --mdc-filled-button-label-text-color: var(--accent-contrast);
+  border-radius: 12px;
+  font-weight: 700;
+}