Refactor workweek presets into dedicated manager

Extracts workweek preset logic from ViewManager into WorkweekPresetsManager

Improves separation of concerns by:
- Creating a dedicated manager for workweek preset UI
- Simplifying ViewManager to focus only on view selector
- Implementing event-driven CSS updates
- Reducing code duplication in ConfigManager

Follows "each UI element has its own manager" architectural principle

src/managers/CalendarManager.ts

@@ -184,11 +184,10 @@ export class CalendarManager {
      * Handle workweek configuration changes
      */
     private handleWorkweekChange(): void {
-
+        // Simply relay the event - workweek info is in the WORKWEEK_CHANGED event
         this.eventBus.emit('workweek:header-update', {
             currentDate: this.currentDate,
-            currentView: this.currentView,
-            workweek: this.config.currentWorkWeek
+            currentView: this.currentView
         });
     }