feat: section 5 — MapLibre map with live track and camera follow

Replace SVG TrackView with a real MapLibre map:
- OpenFreeMap liberty tiles (no API key)
- Camera follows user in course mode while recording
- GeoJSONSource + LineLayer renders track polyline updated live
- UserLocation dot shows current GPS position
- Sensors button overlaid with semi-transparent background

CLAUDE.md

@@ -121,11 +121,9 @@ Items below are what remains before v1 is shippable.
 
 - [x] `src/services/batteryOptimization.ts` — Android-only, one-time prompt (dismissed flag in AsyncStorage); uses `REQUEST_IGNORE_BATTERY_OPTIMIZATIONS` intent to open the system dialog for bincio-rec directly; falls back to `IGNORE_BATTERY_OPTIMIZATION_SETTINGS` (general page) on OEMs that block the direct intent; called from `App.tsx` on mount alongside notification permission request
 
-### 5 — Map (optional upgrade)
+### 5 — Map ✅
 
-The track view from section 1 already shows the GPX polyline scaled to fit the screen.
-MapLibre can be added later for a real basemap (streets/terrain), but is not required for v1.
-
-- [ ] **MapLibre basemap** — replace `TrackView` SVG with `<MapLibreGL.MapView>` + a tile source (e.g. OpenFreeMap); call `MapLibreGL.setAccessToken(null)` for raster-free usage
-- [ ] **Camera follow** — add `<MapLibreGL.Camera>` that follows `trackPoints[last]` during recording
-- [ ] **Line layer** — replace SVG polyline with `<MapLibreGL.ShapeSource>` + `<MapLibreGL.LineLayer>`
+- [x] **MapLibre basemap** — `Map` with OpenFreeMap liberty style (`tiles.openfreemap.org`); no API key required; logo and attribution hidden
+- [x] **Camera follow** — `Camera` with `trackUserLocation="course"` while recording; switches off when idle/paused
+- [x] **Live track line** — `GeoJSONSource` fed a memoized `LineString` from `trackPoints`; `Layer` with `type="line"` and blue stroke rendered on top of the basemap
+- [x] **User location dot** — `UserLocation` component shows current position on map

src/screens/RecordingScreen.tsx

@@ -1,20 +1,29 @@
-import React, { useEffect, useRef, useState } from 'react';
-import { View, Text, StyleSheet, TouchableOpacity, Alert, LayoutChangeEvent } from 'react-native';
+import React, { useEffect, useRef, useState, useMemo } from 'react';
+import { View, Text, StyleSheet, TouchableOpacity, Alert } from 'react-native';
 import { useNavigation } from '@react-navigation/native';
 import { NativeStackNavigationProp } from '@react-navigation/native-stack';
 import { activateKeepAwakeAsync, deactivateKeepAwake } from 'expo-keep-awake';
-import Svg, { Polyline } from 'react-native-svg';
+import { Map, Camera, GeoJSONSource, Layer, UserLocation } from '@maplibre/maplibre-react-native';
+import type { LineLayerStyle } from '@maplibre/maplibre-react-native';
 import { useRecordingStore } from '../store/recording';
 import { startGpsRecording, stopGpsRecording, requestLocationPermissions } from '../services/gps';
 import { RootStackParamList, TrackPoint } from '../types';
 
+const MAP_STYLE = 'https://tiles.openfreemap.org/styles/liberty';
+
+const trackLineStyle: LineLayerStyle = {
+  lineColor: '#3b82f6',
+  lineWidth: 3,
+  lineJoin: 'round',
+  lineCap: 'round',
+};
+
 type Nav = NativeStackNavigationProp<RootStackParamList>;
 
 export function RecordingScreen() {
   const nav = useNavigation<Nav>();
   const { status, ble, keepAwake, trackPoints, start, pause, resume, stop, setKeepAwake, getStats } = useRecordingStore();
   const [stats, setStats] = useState(getStats());
-  const [mapSize, setMapSize] = useState({ width: 0, height: 0 });
   const intervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
 
   useEffect(() => {
@@ -30,6 +39,15 @@ export function RecordingScreen() {
     }
   }, [keepAwake, status]);
 
+  const trackGeoJSON = useMemo<GeoJSON.Feature<GeoJSON.LineString>>(() => ({
+    type: 'Feature',
+    geometry: {
+      type: 'LineString',
+      coordinates: trackPoints.map((p) => [p.lon, p.lat]),
+    },
+    properties: {},
+  }), [trackPoints]);
+
   async function handleStart() {
     const granted = await requestLocationPermissions();
     if (!granted) {
@@ -76,16 +94,20 @@ export function RecordingScreen() {
         <StatBox label="Cadence" value={ble.cadence ? `${ble.cadence} rpm` : '—'} />
       </View>
 
-      <View
-        style={styles.mapArea}
-        onLayout={(e: LayoutChangeEvent) => {
-          const { width, height } = e.nativeEvent.layout;
-          setMapSize({ width, height });
-        }}
-      >
-        {mapSize.width > 0 && (
-          <TrackView trackPoints={trackPoints} width={mapSize.width} height={mapSize.height} />
+      <View style={styles.mapArea}>
+        <Map mapStyle={MAP_STYLE} style={StyleSheet.absoluteFill} logo={false} attribution={false}>
+          <Camera
+            trackUserLocation={status === 'recording' ? 'course' : undefined}
+            initialViewState={{ zoom: 14 }}
+          />
+          <UserLocation />
+          {trackPoints.length >= 2 && (
+            <GeoJSONSource id="track" data={trackGeoJSON}>
+              <Layer id="track-line" type="line" style={trackLineStyle} />
+            </GeoJSONSource>
           )}
+        </Map>
+
         <TouchableOpacity style={styles.sensorBtn} onPress={() => nav.navigate('SensorPairing')}>
           <Text style={styles.sensorBtnText}>⚡ Sensors</Text>
         </TouchableOpacity>
@@ -129,45 +151,6 @@ export function RecordingScreen() {
   );
 }
 
-const PADDING = 16;
-
-function TrackView({ trackPoints, width, height }: { trackPoints: TrackPoint[]; width: number; height: number }) {
-  if (trackPoints.length < 2) {
-    return (
-      <View style={StyleSheet.absoluteFill}>
-        <Text style={styles.mapHint}>
-          {trackPoints.length === 0 ? 'Start recording to see your track' : '…'}
-        </Text>
-      </View>
-    );
-  }
-
-  const lats = trackPoints.map((p) => p.lat);
-  const lons = trackPoints.map((p) => p.lon);
-  const minLat = Math.min(...lats), maxLat = Math.max(...lats);
-  const minLon = Math.min(...lons), maxLon = Math.max(...lons);
-  const latRange = maxLat - minLat || 0.0001;
-  const lonRange = maxLon - minLon || 0.0001;
-
-  const w = width - PADDING * 2;
-  const h = height - PADDING * 2;
-
-  // preserve aspect ratio
-  const scale = Math.min(w / lonRange, h / latRange);
-  const offX = (w - lonRange * scale) / 2 + PADDING;
-  const offY = (h - latRange * scale) / 2 + PADDING;
-
-  const points = trackPoints
-    .map((p) => `${offX + (p.lon - minLon) * scale},${offY + (maxLat - p.lat) * scale}`)
-    .join(' ');
-
-  return (
-    <Svg width={width} height={height} style={StyleSheet.absoluteFill}>
-      <Polyline points={points} fill="none" stroke="#3b82f6" strokeWidth={2} strokeLinejoin="round" strokeLinecap="round" />
-    </Svg>
-  );
-}
-
 function StatBox({ label, value }: { label: string; value: string }) {
   return (
     <View style={styles.statBox}>
@@ -183,9 +166,8 @@ const styles = StyleSheet.create({
   statBox: { width: '25%', padding: 8, alignItems: 'center' },
   statLabel: { color: '#888', fontSize: 11, textTransform: 'uppercase' },
   statValue: { color: '#fff', fontSize: 18, fontWeight: '600', marginTop: 2 },
-  mapArea: { flex: 1, backgroundColor: '#0d0d1a', overflow: 'hidden' },
-  mapHint: { color: '#333', fontSize: 13, textAlign: 'center', marginTop: 40 },
-  sensorBtn: { position: 'absolute', top: 10, right: 10, backgroundColor: '#1e1e2e', borderRadius: 8, paddingVertical: 6, paddingHorizontal: 12 },
+  mapArea: { flex: 1, overflow: 'hidden' },
+  sensorBtn: { position: 'absolute', top: 10, right: 10, backgroundColor: 'rgba(17,17,17,0.85)', borderRadius: 8, paddingVertical: 6, paddingHorizontal: 12 },
   sensorBtnText: { color: '#3b82f6', fontSize: 13, fontWeight: '600' },
   controls: { flexDirection: 'row', alignItems: 'center', justifyContent: 'center', gap: 12, padding: 20 },
   awakeBtn: { backgroundColor: '#1e1e1e', borderRadius: 20, paddingVertical: 8, paddingHorizontal: 14 },