Adds date navigation to scheduled events

Implements date navigation for scheduled events, allowing users to view events for different days.

This change replaces the static "Today's Events" section with a dynamic date selector.
It introduces buttons for navigating to the previous and next days, as well as a "Today" button to return to the current date.
A date display shows the selected date, and a message indicates when there are no scheduled events for a given day.

src/modules/nostr-feed/composables/useScheduledEvents.ts

@@ -31,6 +31,15 @@ export function useScheduledEvents() {
     return scheduledEventService.getEventsForDate(date)
   }
 
+  /**
+   * Get events for a specific date (filtered by current user participation)
+   * @param date - ISO date string (YYYY-MM-DD). Defaults to today.
+   */
+  const getEventsForSpecificDate = (date?: string): ScheduledEvent[] => {
+    if (!scheduledEventService) return []
+    return scheduledEventService.getEventsForSpecificDate(date, currentUserPubkey.value)
+  }
+
   /**
    * Get today's scheduled events (filtered by current user participation)
    */
@@ -141,6 +150,7 @@ export function useScheduledEvents() {
     // Methods
     getScheduledEvents,
     getEventsForDate,
+    getEventsForSpecificDate,
     getTodaysEvents,
     getCompletion,
     isCompleted,