feat(lib): make days protected and readonly

libs/ui/src/lib/historical-market-data-editor/historical-market-data-editor.component.ts

@@ -72,7 +72,6 @@ export class GfHistoricalMarketDataEditorComponent
 
   @Output() marketDataChanged = new EventEmitter<boolean>();
 
-  public days = Array(31);
   public defaultDateFormat: string;
   public deviceType: string;
   public historicalDataForm = this.formBuilder.group({
@@ -91,6 +90,8 @@ export class GfHistoricalMarketDataEditorComponent
     };
   } = {};
 
+  protected readonly days = Array(31);
+
   private unsubscribeSubject = new Subject<void>();
 
   public constructor(