feat: add Expo React Native client scaffold

- Expo SDK 54 / React Native 0.81 with expo-router
- Tailscale devcontainer feature for direct device connectivity
- Dev proxy for React Native DevTools access over Tailscale
- EAS build configuration for development/preview/production
- Ona automation for Expo dev server

Co-authored-by: Ona <no-reply@ona.com>

apps/aris-client/src/app/_layout.tsx

@@ -0,0 +1,23 @@
+import { DarkTheme, DefaultTheme, ThemeProvider } from "@react-navigation/native"
+import { Stack } from "expo-router"
+import { StatusBar } from "expo-status-bar"
+import "react-native-reanimated"
+import { useColorScheme } from "@/hooks/use-color-scheme"
+
+export const unstable_settings = {
+	anchor: "(tabs)",
+}
+
+export default function RootLayout() {
+	const colorScheme = useColorScheme()
+
+	return (
+		<ThemeProvider value={colorScheme === "dark" ? DarkTheme : DefaultTheme}>
+			<Stack>
+				<Stack.Screen name="(tabs)" options={{ headerShown: false }} />
+				<Stack.Screen name="modal" options={{ presentation: "modal", title: "Modal" }} />
+			</Stack>
+			<StatusBar style="auto" />
+		</ThemeProvider>
+	)
+}