Adds resource-based calendar view mode

Introduces new ResourceColumnDataSource and ResourceHeaderRenderer to support column rendering by resources instead of dates

Enables dynamic calendar mode switching between date and resource views
Updates core managers and services to support async column retrieval
Refactors data source interfaces to use Promise-based methods

Improves calendar flexibility and resource management capabilities

src/types/ColumnDataSource.ts

@@ -21,7 +21,7 @@ export interface IColumnDataSource {
    * Get the list of columns to render
    * @returns Array of column information
    */
-  getColumns(): IColumnInfo[];
+  getColumns(): Promise<IColumnInfo[]>;
 
   /**
    * Get the type of columns this datasource provides