feat: Implement RSSI service for iOS and Web platforms

- Added IosRssiService to handle synthetic RSSI data for iOS.
- Created WebRssiService to simulate RSSI scanning on the web.
- Defined shared types for WifiNetwork and RssiService in rssi.service.ts.
- Introduced simulation service to generate synthetic sensing data.
- Implemented WebSocket service for real-time data handling with reconnection logic.
- Established Zustand stores for managing application state related to MAT and pose data.
- Developed theme context and utility functions for consistent styling and formatting.
- Added type definitions for various application entities including API responses and sensing data.
- Created utility functions for color mapping and URL validation.
- Configured TypeScript settings for the mobile application.

ui/mobile/src/navigation/MainTabs.tsx

@@ -0,0 +1,132 @@
+import React, { Suspense } from 'react';
+import { ActivityIndicator } from 'react-native';
+import { createBottomTabNavigator } from '@react-navigation/bottom-tabs';
+import { Ionicons } from '@expo/vector-icons';
+import { ThemedText } from '../components/ThemedText';
+import { ThemedView } from '../components/ThemedView';
+import { colors } from '../theme/colors';
+import { useMatStore } from '../stores/matStore';
+import { MainTabsParamList } from './types';
+
+const createPlaceholder = (label: string) => {
+  const Placeholder = () => (
+    <ThemedView style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
+      <ThemedText preset="bodyLg">{label} screen not implemented yet</ThemedText>
+      <ThemedText preset="bodySm" color="textSecondary">
+        Placeholder shell
+      </ThemedText>
+    </ThemedView>
+  );
+  const LazyPlaceholder = React.lazy(async () => ({ default: Placeholder }));
+
+  const Wrapped = () => (
+    <Suspense
+      fallback={
+        <ThemedView style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
+          <ActivityIndicator color={colors.accent} />
+          <ThemedText preset="bodySm" color="textSecondary" style={{ marginTop: 8 }}>
+            Loading {label}
+          </ThemedText>
+        </ThemedView>
+      }
+    >
+      <LazyPlaceholder />
+    </Suspense>
+  );
+
+  return Wrapped;
+};
+
+const wrapLazy = (
+  loader: () => Promise<{ default: React.ComponentType }>,
+  label: string,
+) => {
+  const fallback = createPlaceholder(label);
+  return React.lazy(async () => {
+    try {
+      const module = await loader();
+      if (module?.default) {
+        return module;
+      }
+    } catch {
+      // keep fallback for shell-only screens
+    }
+    return { default: fallback } as { default: React.ComponentType };
+  });
+};
+
+const LiveScreen = wrapLazy(() => import('../screens/LiveScreen'), 'Live');
+const VitalsScreen = wrapLazy(() => import('../screens/VitalsScreen'), 'Vitals');
+const ZonesScreen = wrapLazy(() => import('../screens/ZonesScreen'), 'Zones');
+const MATScreen = wrapLazy(() => import('../screens/MATScreen'), 'MAT');
+const SettingsScreen = wrapLazy(() => import('../screens/SettingsScreen'), 'Settings');
+
+const toIconName = (routeName: keyof MainTabsParamList) => {
+  switch (routeName) {
+    case 'Live':
+      return 'wifi';
+    case 'Vitals':
+      return 'heart';
+    case 'Zones':
+      return 'grid';
+    case 'MAT':
+      return 'shield-checkmark';
+    case 'Settings':
+      return 'settings';
+    default:
+      return 'ellipse';
+  }
+};
+
+const screens: ReadonlyArray<{ name: keyof MainTabsParamList; component: React.ComponentType }> = [
+  { name: 'Live', component: LiveScreen },
+  { name: 'Vitals', component: VitalsScreen },
+  { name: 'Zones', component: ZonesScreen },
+  { name: 'MAT', component: MATScreen },
+  { name: 'Settings', component: SettingsScreen },
+];
+
+const Tab = createBottomTabNavigator<MainTabsParamList>();
+
+const Suspended = ({ component: Component }: { component: React.ComponentType }) => (
+  <Suspense fallback={<ActivityIndicator color={colors.accent} />}>
+    <Component />
+  </Suspense>
+);
+
+export const MainTabs = () => {
+  const matAlertCount = useMatStore((state) => state.alerts.length);
+
+  return (
+    <Tab.Navigator
+      screenOptions={({ route }) => ({
+        headerShown: false,
+        tabBarActiveTintColor: colors.accent,
+        tabBarInactiveTintColor: colors.textSecondary,
+        tabBarStyle: {
+          backgroundColor: '#0D1117',
+          borderTopColor: colors.border,
+          borderTopWidth: 1,
+        },
+        tabBarIcon: ({ color, size }) => <Ionicons name={toIconName(route.name)} size={size} color={color} />,
+        tabBarLabelStyle: {
+          fontFamily: 'Courier New',
+          textTransform: 'uppercase',
+          fontSize: 10,
+        },
+        tabBarLabel: ({ children, color }) => <ThemedText style={{ color }}>{children}</ThemedText>,
+      })}
+    >
+      {screens.map(({ name, component }) => (
+        <Tab.Screen
+          key={name}
+          name={name}
+          options={{
+            tabBarBadge: name === 'MAT' ? (matAlertCount > 0 ? matAlertCount : undefined) : undefined,
+          }}
+          component={() => <Suspended component={component} />}
+        />
+      ))}
+    </Tab.Navigator>
+  );
+};

ui/mobile/src/navigation/RootNavigator.tsx

@@ -0,0 +1,5 @@
+import { MainTabs } from './MainTabs';
+
+export const RootNavigator = () => {
+  return <MainTabs />;
+};

ui/mobile/src/navigation/types.ts

@@ -0,0 +1,11 @@
+export type RootStackParamList = {
+  MainTabs: undefined;
+};
+
+export type MainTabsParamList = {
+  Live: undefined;
+  Vitals: undefined;
+  Zones: undefined;
+  MAT: undefined;
+  Settings: undefined;
+};