Remove debug logging from RRULE handling

Clean up extensive console logging that was added during RRULE debugging.
Removed debug logs from:
- Frontend RRULE generation in create event modal
- Frontend RRULE parsing in calendar service
- Weekly/monthly/yearly occurrence generation functions
- Backend RRULE processing in events and series handlers

The core functionality remains unchanged - this is purely a cleanup
of temporary debugging output that is no longer needed.

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

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

backend/src/handlers/series.rs

@@ -164,16 +164,13 @@ pub async fn create_event_series(
     // Check if recurrence is already a full RRULE or just a simple type
     let rrule = if request.recurrence.starts_with("FREQ=") {
         // Frontend sent a complete RRULE string, use it directly
-        println!("🎯 SERIES: Using complete RRULE from frontend: {}", request.recurrence);
         request.recurrence.clone()
     } else {
         // Legacy path: Generate the RRULE for recurrence
-        println!("🔄 SERIES: Building RRULE from simple recurrence type: {}", request.recurrence);
         build_series_rrule_with_freq(&request, recurrence_freq)?
     };
     event.rrule = Some(rrule);
 
-    println!("🔁 Generated RRULE: {:?}", event.rrule);
 
     // Create the event on the CalDAV server
     let event_href = client.create_event(&calendar_path, &event)