Refactors grid date handling and event rendering

Replaces getPeriodRange with getDisplayDates approach
Simplifies event rendering by using flexible date array
Updates event rendering to work with dynamic date lists

Improves code modularity and reduces complexity

src/types/ManagerTypes.ts

@@ -40,7 +40,6 @@ export interface IEventRenderingService extends IManager {
 
 export interface IGridManager extends IManager {
   render(): Promise<void>;
-  getDisplayDates(): Date[];
 }
 
 export interface IScrollManager extends IManager {