Implement complete recurring event deletion with EXDATE and RRULE UNTIL support

Frontend Changes:
- Add DeleteAction enum with DeleteThis, DeleteFollowing, DeleteSeries options
- Update EventContextMenu to show different delete options for recurring events
- Add exception_dates field to CalendarEvent struct
- Fix occurrence generation to respect EXDATE exclusions
- Add comprehensive RRULE parsing with UNTIL date support
- Fix UNTIL date parsing to handle backend format (YYYYMMDDTHHMMSSZ)
- Enhanced debugging for RRULE processing and occurrence generation

Backend Changes:
- Add exception_dates field to CalendarEvent struct with EXDATE parsing/generation
- Implement update_event method for CalDAV client
- Add fetch_event_by_href helper function
- Update DeleteEventRequest model with delete_action and occurrence_date fields
- Implement proper delete_this logic with EXDATE addition
- Implement delete_following logic with RRULE UNTIL modification
- Add comprehensive logging for delete operations

CalDAV Integration:
- Proper EXDATE generation in iCal format for excluded occurrences
- RRULE modification with UNTIL clause for partial series deletion
- Event updating via CalDAV PUT operations
- Full iCal RFC 5545 compliance for recurring event modifications

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

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

src/components/mod.rs

@@ -15,7 +15,7 @@ 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 event_context_menu::{EventContextMenu, DeleteAction};
 pub use calendar_context_menu::CalendarContextMenu;
 pub use create_event_modal::{CreateEventModal, EventCreationData, EventStatus, EventClass, ReminderType, RecurrenceType};
 pub use sidebar::Sidebar;