Implement event deletion with right-click context menu

- Add EventContextMenu component with delete option
- Create DELETE /api/calendar/events/delete endpoint
- Implement CalDAV event deletion in backend
- Add proper URL construction for CalDAV event hrefs
- Integrate context menu with calendar event right-clicks
- Auto-refresh UI after successful event deletion

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/components/mod.rs

@@ -3,6 +3,7 @@ pub mod calendar;
 pub mod event_modal;
 pub mod create_calendar_modal;
 pub mod context_menu;
+pub mod event_context_menu;
 pub mod sidebar;
 pub mod calendar_list_item;
 pub mod route_handler;
@@ -12,6 +13,7 @@ pub use calendar::Calendar;
 pub use event_modal::EventModal;
 pub use create_calendar_modal::CreateCalendarModal;
 pub use context_menu::ContextMenu;
+pub use event_context_menu::EventContextMenu;
 pub use sidebar::Sidebar;
 pub use calendar_list_item::CalendarListItem;
 pub use route_handler::RouteHandler;