feat(mobile): Add field app with date range navigation

- Add React Native Expo field app for mobile staff
- Use main /appointments/ endpoint with date range support
- Add X-Business-Subdomain header for tenant context
- Support day/week view navigation
- Remove WebSocket console logging from frontend
- Update AppointmentStatus type to include all backend statuses
- Add responsive status legend to scheduler header

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mobile/field-app/app/_layout.tsx

@@ -0,0 +1,38 @@
+/**
+ * Root Layout
+ *
+ * Sets up providers and global configuration.
+ */
+
+import { Stack } from 'expo-router';
+import { StatusBar } from 'expo-status-bar';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { SafeAreaProvider } from 'react-native-safe-area-context';
+import { AuthProvider } from '../src/hooks/useAuth';
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      retry: 2,
+      staleTime: 1000 * 60 * 5, // 5 minutes
+    },
+  },
+});
+
+export default function RootLayout() {
+  return (
+    <SafeAreaProvider>
+      <QueryClientProvider client={queryClient}>
+        <AuthProvider>
+          {/* translucent={false} ensures content doesn't render behind status bar on Android */}
+          <StatusBar style="light" translucent={false} backgroundColor="#2563eb" />
+          <Stack screenOptions={{ headerShown: false }}>
+            <Stack.Screen name="index" />
+            <Stack.Screen name="login" />
+            <Stack.Screen name="(auth)" />
+          </Stack>
+        </AuthProvider>
+      </QueryClientProvider>
+    </SafeAreaProvider>
+  );
+}