Supports dynamic event types; refactors navigation DOM access

Enables dynamic event types by reading the 'type' field from raw event data instead of using a hardcoded value.

Removes DOM element caching for calendar and grid containers in the navigation manager, opting for direct DOM queries. Eliminates associated cache clearing and post-animation header event emission.

src/managers/EventManager.ts

@@ -10,6 +10,7 @@ interface RawEventData {
   title: string;
   start: string | Date;
   end: string | Date;
+  type : string;
   color?: string;
   allDay?: boolean;
   [key: string]: unknown;
@@ -88,7 +89,7 @@ export class EventManager {
             ...event,
             start: new Date(event.start),
             end: new Date(event.end),
-            type: 'event',
+            type : event.type,
             allDay: event.allDay || false,
             syncStatus: 'synced' as const
         }));