Refactor calendar datasource architecture

Centralizes date calculation logic into DateColumnDataSource
Improves separation of concerns across rendering components

Key changes:
- Introduces IColumnInfo interface for flexible column data
- Moves date calculation from multiple managers to dedicated datasource
- Removes duplicate date rendering logic
- Prepares architecture for future resource-based views

src/types/ColumnDataSource.ts

@@ -1,3 +1,12 @@
+/**
+ * Column information container
+ * Contains both identifier and actual data for a column
+ */
+export interface IColumnInfo {
+  identifier: string;      // "2024-11-13" (date mode) or "person-1" (resource mode)
+  data: Date | any;        // Date for date-mode, IResource for resource-mode
+}
+
 /**
  * IColumnDataSource - Defines the contract for providing column data
  *
@@ -6,10 +15,10 @@
  */
 export interface IColumnDataSource {
   /**
-   * Get the list of column identifiers to render
-   * @returns Array of identifiers (dates or resource IDs)
+   * Get the list of columns to render
+   * @returns Array of column information
    */
-  getColumns(): Date[];
+  getColumns(): IColumnInfo[];
 
   /**
    * Get the type of columns this datasource provides