Fix single event deletion functionality with proper recurring vs non-recurring handling

This commit resolves multiple issues with event deletion:

Backend fixes:
- Fix CalDAV URL construction for DELETE requests (missing slash separator)
- Improve event lookup by href with exact matching and fallback to UID extraction
- Add support for both RFC3339 and simple YYYY-MM-DD date formats in occurrence parsing
- Implement proper logic to distinguish recurring vs non-recurring events in delete_this action
- For non-recurring events: delete entire event from CalDAV server
- For recurring events: add EXDATE to exclude specific occurrences
- Add comprehensive debug logging for troubleshooting deletion issues

Frontend fixes:
- Update callback signatures to support series endpoint parameters (7-parameter tuples)
- Add update_series method to CalendarService for series-specific operations
- Route single occurrence modifications through series endpoint with proper scoping
- Fix all component prop definitions to use new callback signature
- Update all emit calls to pass correct number of parameters

The deletion process now works correctly:
- Single events are completely removed from the calendar
- Recurring event occurrences are properly excluded via EXDATE
- Debug logging helps identify and resolve CalDAV communication issues

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

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

frontend/src/components/calendar.rs

@@ -25,7 +25,7 @@ pub struct CalendarProps {
     #[prop_or_default]
     pub on_create_event_request: Option<Callback<EventCreationData>>,
     #[prop_or_default]
-    pub on_event_update_request: Option<Callback<(VEvent, chrono::NaiveDateTime, chrono::NaiveDateTime, bool, Option<chrono::DateTime<chrono::Utc>>)>>,
+    pub on_event_update_request: Option<Callback<(VEvent, chrono::NaiveDateTime, chrono::NaiveDateTime, bool, Option<chrono::DateTime<chrono::Utc>>, Option<String>, Option<String>)>>,
     #[prop_or_default]
     pub context_menus_open: bool,
 }
@@ -195,9 +195,9 @@ pub fn Calendar(props: &CalendarProps) -> Html {
     // Handle drag-to-move event
     let on_event_update = {
         let on_event_update_request = props.on_event_update_request.clone();
-        Callback::from(move |(event, new_start, new_end, preserve_rrule, until_date): (VEvent, chrono::NaiveDateTime, chrono::NaiveDateTime, bool, Option<chrono::DateTime<chrono::Utc>>)| {
+        Callback::from(move |(event, new_start, new_end, preserve_rrule, until_date, update_scope, occurrence_date): (VEvent, chrono::NaiveDateTime, chrono::NaiveDateTime, bool, Option<chrono::DateTime<chrono::Utc>>, Option<String>, Option<String>)| {
             if let Some(callback) = &on_event_update_request {
-                callback.emit((event, new_start, new_end, preserve_rrule, until_date));
+                callback.emit((event, new_start, new_end, preserve_rrule, until_date, update_scope, occurrence_date));
             }
         })
     };