feat: Phase 3 — services, stores, navigation, design system

Services: ws.service, api.service, simulation.service, rssi.service (android+ios)
Stores: poseStore, settingsStore, matStore (Zustand)
Types: sensing, mat, api, navigation
Hooks: usePoseStream, useRssiScanner, useServerReachability
Theme: colors, typography, spacing, ThemeContext
Navigation: MainTabs (5 tabs), RootNavigator, types
Components: GaugeArc, SparklineChart, OccupancyGrid, StatusDot, ConnectionBanner, SignalBar, +more
Utils: ringBuffer, colorMap, formatters, urlValidator

Verified: tsc 0 errors, jest passes

mobile/App.tsx

@@ -1,25 +1,38 @@
-import React from 'react';
-import { StyleSheet, Text, View } from 'react-native';
+import { useEffect } from 'react';
+import { NavigationContainer, DarkTheme } from '@react-navigation/native';
+import { GestureHandlerRootView } from 'react-native-gesture-handler';
 import { StatusBar } from 'expo-status-bar';
+import { SafeAreaProvider } from 'react-native-safe-area-context';
+import { ThemeProvider } from './src/theme/ThemeContext';
+import { RootNavigator } from './src/navigation/RootNavigator';
 
 export default function App() {
+  useEffect(() => {
+    (globalThis as { __appStartTime?: number }).__appStartTime = Date.now();
+  }, []);
+
+  const navigationTheme = {
+    ...DarkTheme,
+    colors: {
+      ...DarkTheme.colors,
+      background: '#0A0E1A',
+      card: '#0D1117',
+      text: '#E2E8F0',
+      border: '#1E293B',
+      primary: '#32B8C6',
+    },
+  };
+
   return (
-    <View style={styles.container}>
-      <Text style={styles.title}>WiFi-DensePose</Text>
-      <StatusBar style="dark" />
-    </View>
+    <GestureHandlerRootView style={{ flex: 1 }}>
+      <SafeAreaProvider>
+        <ThemeProvider>
+          <NavigationContainer theme={navigationTheme}>
+            <RootNavigator />
+          </NavigationContainer>
+        </ThemeProvider>
+      </SafeAreaProvider>
+      <StatusBar style="light" />
+    </GestureHandlerRootView>
   );
 }
-
-const styles = StyleSheet.create({
-  container: {
-    flex: 1,
-    alignItems: 'center',
-    justifyContent: 'center',
-    backgroundColor: '#fff',
-  },
-  title: {
-    fontSize: 24,
-    fontWeight: '600',
-  },
-});