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/src/theme/colors.ts

@@ -0,0 +1,22 @@
+export const colors = {
+  bg: '#0A0E1A',
+  surface: '#111827',
+  surfaceAlt: '#1A2233',
+  accent: '#32B8C6',
+  accentDim: '#1A6B73',
+  danger: '#FF4757',
+  warn: '#FFA502',
+  success: '#2ED573',
+  textPrimary: '#E2E8F0',
+  textSecondary: '#94A3B8',
+  muted: '#475569',
+  border: '#1E293B',
+  connected: '#2ED573',
+  simulated: '#FFA502',
+  disconnected: '#FF4757',
+  signalLow: '#3B82F6',
+  signalMid: '#10B981',
+  signalHigh: '#EF4444',
+};
+
+export type ColorKey = keyof typeof colors;