Implement comprehensive calendar UX improvements

- Add time range display to week view events showing "start - end" format
- Optimize time display with smart AM/PM formatting to reduce redundancy
- Fix context menu overlap by adding stop_propagation to event handlers
- Implement persistent view mode (Month/Week) across page refreshes using localStorage
- Replace month-based tracking with intelligent selected date tracking
- Add day selection in month view with visual feedback and click handlers
- Fix view switching to navigate to week containing selected day, not first week of month
- Separate selected_date from display_date for proper context switching
- Simplify week view header to show "Month Year" instead of "Week of Month Day"
- Add backward compatibility for existing localStorage keys

Greatly improves calendar navigation and user experience with persistent state

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

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

src/components/month_view.rs

@@ -18,6 +18,10 @@ pub struct MonthViewProps {
     pub on_event_context_menu: Option<Callback<(web_sys::MouseEvent, CalendarEvent)>>,
     #[prop_or_default]
     pub on_calendar_context_menu: Option<Callback<(web_sys::MouseEvent, NaiveDate)>>,
+    #[prop_or_default]
+    pub selected_date: Option<NaiveDate>,
+    #[prop_or_default]
+    pub on_day_select: Option<Callback<NaiveDate>>,
 }
 
 #[function_component(MonthView)]
@@ -65,11 +69,27 @@ pub fn month_view(props: &MonthViewProps) -> Html {
                 (1..=days_in_month).map(|day| {
                     let date = props.current_month.with_day(day).unwrap();
                     let is_today = date == props.today;
+                    let is_selected = props.selected_date == Some(date);
                     let day_events = props.events.get(&date).cloned().unwrap_or_default();
                     
                     html! {
                         <div 
-                            class={classes!("calendar-day", if is_today { Some("today") } else { None })}
+                            class={classes!(
+                                "calendar-day", 
+                                if is_today { Some("today") } else { None },
+                                if is_selected { Some("selected") } else { None }
+                            )}
+                            onclick={
+                                if let Some(callback) = &props.on_day_select {
+                                    let callback = callback.clone();
+                                    Some(Callback::from(move |e: web_sys::MouseEvent| {
+                                        e.stop_propagation(); // Prevent other handlers
+                                        callback.emit(date);
+                                    }))
+                                } else {
+                                    None
+                                }
+                            }
                             oncontextmenu={
                                 if let Some(callback) = &props.on_calendar_context_menu {
                                     let callback = callback.clone();