Better architectural distinction between live coding mode and composition mode

src/lib/stores/uiState.svelte.ts

@@ -10,6 +10,7 @@ export class UIState {
   audioPermissionPopupVisible = $state(true);
   unsavedChangesDialogVisible = $state(false);
   saveAsDialogVisible = $state(false);
+  templateDialogVisible = $state(false);
 
   shareUrl = $state('');
 
@@ -59,4 +60,12 @@ export class UIState {
   hideSaveAsDialog() {
     this.saveAsDialogVisible = false;
   }
+
+  showTemplateDialog() {
+    this.templateDialogVisible = true;
+  }
+
+  hideTemplateDialog() {
+    this.templateDialogVisible = false;
+  }
 }