Add print preview modal with hour range selection

Implements comprehensive print functionality for calendar views:
- Print preview modal with live preview and zoom controls
- Hour range selection for week view (start/end hours)
- Print-specific CSS to hide UI elements and optimize layout
- Event repositioning to align with visible time labels
- Support for both 30-minute and 15-minute time increments
- Mouse wheel zoom functionality in preview

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

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

frontend/src/components/calendar_header.rs

@@ -14,6 +14,8 @@ pub struct CalendarHeaderProps {
     pub time_increment: Option<u32>,
     #[prop_or_default]
     pub on_time_increment_toggle: Option<Callback<MouseEvent>>,
+    #[prop_or_default]
+    pub on_print: Option<Callback<MouseEvent>>,
 }
 
 #[function_component(CalendarHeader)]
@@ -39,6 +41,17 @@ pub fn calendar_header(props: &CalendarHeaderProps) -> Html {
                         html! {}
                     }
                 }
+                {
+                    if let Some(print_callback) = &props.on_print {
+                        html! {
+                            <button class="print-button" onclick={print_callback.clone()} title="Print Calendar">
+                                {"🖨️"}
+                            </button>
+                        }
+                    } else {
+                        html! {}
+                    }
+                }
             </div>
             <h2 class="month-year">{title}</h2>
             <div class="header-right">