Use @gorhom/bottom-sheet for waypoint sheet

Replace custom View-based bottom sheet with @gorhom/bottom-sheet:
- Native gesture-driven drag, snap points, pan-down-to-close
- Proper safe area handling built in
- Wrap app with GestureHandlerRootView
- Add react-native-reanimated plugin to Expo config

Adds react-native-reanimated and react-native-gesture-handler as
native dependencies (requires new EAS build).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mobile/app/_layout.tsx

@@ -1,5 +1,6 @@
 import { useEffect, useState } from "react";
 import { Stack, router } from "expo-router";
+import { GestureHandlerRootView } from "react-native-gesture-handler";
 import { Sentry, initSentry } from "../lib/sentry";
 import { isAuthenticated } from "../lib/auth";
 import { startVersionCheck } from "../lib/version-check";
@@ -22,7 +23,11 @@ function RootLayout() {
 
   if (!checked) return null;
 
-  return <Stack screenOptions={{ headerShown: false }} />;
+  return (
+    <GestureHandlerRootView style={{ flex: 1 }}>
+      <Stack screenOptions={{ headerShown: false }} />
+    </GestureHandlerRootView>
+  );
 }
 
 export default Sentry.wrap(RootLayout);

apps/mobile/app/routes/[id].tsx

@@ -172,15 +172,13 @@ function RouteDetailContent({ route }: { route: RouteDetail }) {
           )}
 
           {selectedWaypoint !== null && editor.waypoints[selectedWaypoint] && (
-            <View style={[styles.sheetOverlay, { paddingBottom: insets.bottom }]}>
-              <WaypointSheet
-                waypoint={editor.waypoints[selectedWaypoint]!}
-                index={selectedWaypoint}
-                onClose={() => setSelectedWaypoint(null)}
-                onDelete={editor.deleteWaypoint}
-                onToggleOvernight={editor.toggleOvernight}
-              />
-            </View>
+            <WaypointSheet
+              waypoint={editor.waypoints[selectedWaypoint]!}
+              index={selectedWaypoint}
+              onClose={() => setSelectedWaypoint(null)}
+              onDelete={editor.deleteWaypoint}
+              onToggleOvernight={editor.toggleOvernight}
+            />
           )}
         </View>
       ) : (
@@ -253,5 +251,4 @@ const styles = StyleSheet.create({
   actionSecondaryText: { color: "#333", fontSize: 16, fontWeight: "600" },
   errorBanner: { position: "absolute", bottom: 16, alignSelf: "center", backgroundColor: "rgba(220,38,38,0.9)", borderRadius: 8, paddingVertical: 8, paddingHorizontal: 16 },
   errorBannerText: { color: "#fff", fontSize: 13 },
-  sheetOverlay: { position: "absolute", bottom: 0, left: 0, right: 0 },
 });