feat: Phase 4 — Live, Vitals, Zones, MAT, Settings screens

LiveScreen: GaussianSplatWebView + gaussian-splats.html (Three.js 3D viz), LiveHUD
VitalsScreen: BreathingGauge, HeartRateGauge, MetricCard (Reanimated arcs)
ZonesScreen: FloorPlanSvg (SVG heatmap 20x20), ZoneLegend, useOccupancyGrid
MATScreen: MatWebView + mat-dashboard.html (pure-JS disaster response), AlertCard/List, SurvivorCounter
SettingsScreen: ServerUrlInput (URL validation + test), ThemePicker, RssiToggle

Verified: tsc 0 errors, jest passes

mobile/src/screens/MATScreen/AlertList.tsx

@@ -0,0 +1,41 @@
+import { FlatList, View } from 'react-native';
+import { ThemedText } from '@/components/ThemedText';
+import { colors } from '@/theme/colors';
+import { spacing } from '@/theme/spacing';
+import type { Alert } from '@/types/mat';
+import { AlertCard } from './AlertCard';
+
+type AlertListProps = {
+  alerts: Alert[];
+};
+
+export const AlertList = ({ alerts }: AlertListProps) => {
+  if (alerts.length === 0) {
+    return (
+      <View
+        style={{
+          alignItems: 'center',
+          justifyContent: 'center',
+          padding: spacing.md,
+          borderWidth: 1,
+          borderColor: colors.border,
+          borderRadius: 12,
+          backgroundColor: '#111827',
+        }}
+      >
+        <ThemedText preset="bodyMd">No alerts — system nominal</ThemedText>
+      </View>
+    );
+  }
+
+  return (
+    <FlatList
+      data={alerts}
+      keyExtractor={(item) => item.id}
+      renderItem={({ item }) => <AlertCard alert={item} />}
+      contentContainerStyle={{ paddingBottom: spacing.md }}
+      showsVerticalScrollIndicator={false}
+      removeClippedSubviews={false}
+    />
+  );
+};