feat(mobile): Netralax landing screen with runtime version + nav smoke test

apps/mobile/app/index.tsx

@@ -1,17 +1,29 @@
-// Landing / Login screen.
+import * as Application from 'expo-application';
+import { Link } from 'expo-router';
+import { Pressable, StyleSheet, Text, View } from 'react-native';
+
+// Phase 0 landing screen. Just enough to prove the app boots and routes:
+//   * Netralax brand wordmark (replaces the previous "ChatApp" string).
+//   * Runtime version from expo-application so we can spot stale builds
+//     on a TestFlight tester's device at a glance.
+//   * Placeholder nav link into (app)/chats — exercises Expo Router so a
+//     routing regression shows up here instead of mid-Phase-1.
 //
-// Milestone 1 TODO:
+// Phase 1 replaces this with the actual magic-link login form.
-// - Show app logo + "Enter your email" field.
-// - On submit, call shared/auth requestMagicLink(email).
-// - Handle deep link return in app/_layout.tsx (or a dedicated auth callback route).
-
-import { StyleSheet, Text, View } from 'react-native';
-
 export default function Landing() {
+  const version = Application.nativeApplicationVersion ?? '0.0.0';
+
   return (
     <View style={styles.container}>
-      <Text style={styles.title}>ChatApp</Text>
+      <Text style={styles.title}>Netralax</Text>
-      <Text style={styles.subtitle}>Login placeholder — magic link flow goes here.</Text>
+      <Text style={styles.subtitle}>Phase 0 — Deployment-Fundament</Text>
+      <Text style={styles.version}>v{version}</Text>
+
+      <Link href="/(app)/chats" asChild>
+        <Pressable style={styles.button}>
+          <Text style={styles.buttonText}>Weiter (Smoke-Test)</Text>
+        </Pressable>
+      </Link>
     </View>
   );
 }
@@ -24,6 +36,14 @@ const styles = StyleSheet.create({
     backgroundColor: '#0b0b0f',
     padding: 24,
   },
-  title: { color: '#fff', fontSize: 28, fontWeight: '600' },
+  title: { color: '#fff', fontSize: 32, fontWeight: '700', letterSpacing: 1 },
-  subtitle: { color: '#9ca3af', marginTop: 8, textAlign: 'center' },
+  subtitle: { color: '#9ca3af', marginTop: 8, marginBottom: 4 },
+  version: { color: '#6b7280', fontSize: 12, marginBottom: 32 },
+  button: {
+    backgroundColor: '#5865f2',
+    paddingHorizontal: 24,
+    paddingVertical: 14,
+    borderRadius: 12,
+  },
+  buttonText: { color: '#fff', fontWeight: '600', fontSize: 15 },
 });