feat(mobile): implement event switcher sheet in header

- Replaced direct navigation with a bottom sheet for event switching
- Created reusable EventSwitcherSheet component
- Preserves context when switching events

resources/js/admin/mobile/components/MobileShell.tsx

@@ -21,6 +21,7 @@ import { loadPhotoQueue } from '../lib/photoModerationQueue';
 import { countQueuedPhotoActions } from '../lib/queueStatus';
 import { useAdminTheme } from '../theme';
 import { useAuth } from '../../auth/context';
+import { EventSwitcherSheet } from './EventSwitcherSheet';
 
 type MobileShellProps = {
   title?: string;
@@ -55,6 +56,7 @@ export function MobileShell({ title, subtitle, children, activeTab, onBack, head
   const [loadingEvents, setLoadingEvents] = React.useState(false);
   const [attemptedFetch, setAttemptedFetch] = React.useState(false);
   const [queuedPhotoCount, setQueuedPhotoCount] = React.useState(0);
+  const [switcherOpen, setSwitcherOpen] = React.useState(false);
 
   const effectiveEvents = events.length ? events : fallbackEvents;
   const effectiveActive = activeEvent ?? (effectiveEvents.length === 1 ? effectiveEvents[0] : null);
@@ -136,7 +138,7 @@ export function MobileShell({ title, subtitle, children, activeTab, onBack, head
     }
 
     return (
-      <Pressable onPress={() => navigate(ADMIN_EVENTS_PATH)}>
+      <Pressable onPress={() => setSwitcherOpen(true)}>
         <XStack 
            backgroundColor="rgba(255, 255, 255, 0.12)" 
            paddingHorizontal="$3" 
@@ -334,6 +336,13 @@ export function MobileShell({ title, subtitle, children, activeTab, onBack, head
       </YStack>
 
       <BottomNav active={activeTab} onNavigate={go} />
+      
+      <EventSwitcherSheet
+         open={switcherOpen}
+         onClose={() => setSwitcherOpen(false)}
+         events={effectiveEvents}
+         activeSlug={effectiveActive?.slug ?? null}
+      />
     </YStack>
   );
 }
@@ -364,4 +373,4 @@ export function HeaderActionButton({
       {children}
     </Pressable>
   );
-}
+}