Implement shared RFC 5545 VEvent library with workspace restructuring

- Created calendar-models/ shared library with RFC 5545-compliant VEvent structures
- Migrated backend to use shared VEvent with proper field mappings (dtstart/dtend, rrule, exdate, etc.)
- Converted CalDAV client to parse into VEvent structures with structured types
- Updated all CRUD handlers to use VEvent with CalendarUser, Attendee, VAlarm types
- Restructured project as Cargo workspace with frontend/, backend/, calendar-models/
- Updated Trunk configuration for new directory structure
- Fixed all compilation errors and field references throughout codebase
- Updated documentation and build instructions for workspace structure

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

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

frontend/src/components/recurring_edit_modal.rs

@@ -0,0 +1,93 @@
+use yew::prelude::*;
+use chrono::NaiveDateTime;
+use crate::models::ical::VEvent;
+
+#[derive(Clone, PartialEq)]
+pub enum RecurringEditAction {
+    ThisEvent,
+    FutureEvents,
+    AllEvents,
+}
+
+#[derive(Properties, PartialEq)]
+pub struct RecurringEditModalProps {
+    pub show: bool,
+    pub event: VEvent,
+    pub new_start: NaiveDateTime,
+    pub new_end: NaiveDateTime,
+    pub on_choice: Callback<RecurringEditAction>,
+    pub on_cancel: Callback<()>,
+}
+
+#[function_component(RecurringEditModal)]
+pub fn recurring_edit_modal(props: &RecurringEditModalProps) -> Html {
+    if !props.show {
+        return html! {};
+    }
+
+    let event_title = props.event.summary.as_ref().map(|s| s.as_str()).unwrap_or("Untitled Event");
+    
+    let on_this_event = {
+        let on_choice = props.on_choice.clone();
+        Callback::from(move |_| {
+            on_choice.emit(RecurringEditAction::ThisEvent);
+        })
+    };
+    
+    let on_future_events = {
+        let on_choice = props.on_choice.clone();
+        Callback::from(move |_| {
+            on_choice.emit(RecurringEditAction::FutureEvents);
+        })
+    };
+    
+    let on_all_events = {
+        let on_choice = props.on_choice.clone();
+        Callback::from(move |_| {
+            on_choice.emit(RecurringEditAction::AllEvents);
+        })
+    };
+    
+    let on_cancel = {
+        let on_cancel = props.on_cancel.clone();
+        Callback::from(move |_| {
+            on_cancel.emit(());
+        })
+    };
+
+    html! {
+        <div class="modal-backdrop">
+            <div class="modal-content recurring-edit-modal">
+                <div class="modal-header">
+                    <h3>{"Edit Recurring Event"}</h3>
+                </div>
+                <div class="modal-body">
+                    <p>{format!("You're modifying \"{}\" which is part of a recurring series.", event_title)}</p>
+                    <p>{"How would you like to apply this change?"}</p>
+                    
+                    <div class="recurring-edit-options">
+                        <button class="btn btn-primary recurring-option" onclick={on_this_event}>
+                            <div class="option-title">{"This event only"}</div>
+                            <div class="option-description">{"Change only this occurrence"}</div>
+                        </button>
+                        
+                        <button class="btn btn-primary recurring-option" onclick={on_future_events}>
+                            <div class="option-title">{"This and future events"}</div>
+                            <div class="option-description">{"Change this occurrence and all future occurrences"}</div>
+                        </button>
+                        
+                        <button class="btn btn-primary recurring-option" onclick={on_all_events}>
+                            <div class="option-title">{"All events in series"}</div>
+                            <div class="option-description">{"Change all occurrences in the series"}</div>
+                        </button>
+                    </div>
+                </div>
+                <div class="modal-footer">
+                    <button class="btn btn-secondary" onclick={on_cancel}>
+                        {"Cancel"}
+                    </button>
+                </div>
+            </div>
+        </div>
+    }
+}