Complete event modal migration: remove original and rename V2

Remove the original create_event_modal.rs and rename create_event_modal_v2.rs
to complete the modal migration started earlier. This eliminates duplicate code
and consolidates to a single, clean event modal implementation.

Changes:
- Remove original create_event_modal.rs (2,300+ lines)
- Rename create_event_modal_v2.rs → create_event_modal.rs
- Update component/function names: CreateEventModalV2 → CreateEventModal
- Fix all imports in app.rs and calendar.rs
- Add missing to_create_event_params() method to EventCreationData
- Resolve EditAction type conflicts between modules
- Clean up duplicate types and unused imports
- Maintain backwards compatibility with EventCreationData export

Result: -2440 lines, +160 lines - massive code cleanup with zero functionality loss.

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

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

frontend/src/components/calendar.rs

@@ -1,5 +1,5 @@
 use crate::components::{
-    CalendarHeader, CreateEventModalV2, EventCreationData, EventModal, MonthView, ViewMode, WeekView,
+    CalendarHeader, CreateEventModal, EventCreationData, EventModal, MonthView, ViewMode, WeekView,
 };
 use crate::models::ical::VEvent;
 use crate::services::{calendar_service::UserInfo, CalendarService};
@@ -492,7 +492,7 @@ pub fn Calendar(props: &CalendarProps) -> Html {
             />
 
             // Create event modal
-            <CreateEventModalV2
+            <CreateEventModal
                 is_open={*show_create_modal}
                 selected_date={create_event_data.as_ref().map(|(date, _, _)| *date)}
                 event_to_edit={None}