fix: render isolated route acceleration and braking events

lib/features/map/map_screen.dart

@@ -309,32 +309,63 @@ class _MapScreenState extends ConsumerState<MapScreen> {
     required String idPrefix,
     required Color color,
   }) {
+    if (samples.isEmpty) return [];
+
+    // A threshold crossing is often only one telemetry sample wide.  Requiring
+    // two consecutive qualifying samples made isolated acceleration/braking
+    // events disappear from the map.  Build event runs, then include one GPS
+    // sample on each side so every event renders as a visible route segment.
     final polylines = <AppPolyline>[];
-    List<AppLatLng> segment = [];
+    final eventIndices = <int>[];
+
+    for (var i = 0; i < samples.length; i++) {
+      final g = samples[i].longitudinalG ?? samples[i].accelX;
+      if (g != null && g.isFinite && predicate(g)) {
+        eventIndices.add(i);
+      }
+    }
+    if (eventIndices.isEmpty) return polylines;
+
+    var runStart = eventIndices.first;
+    var runEnd = eventIndices.first;
     var segmentIndex = 0;
 
-    void flush() {
-      if (segment.length >= 2) {
+    void emitRun(int start, int end) {
+      final expandedStart = start > 0 ? start - 1 : start;
+      final expandedEnd = end < samples.length - 1 ? end + 1 : end;
+      final points = <AppLatLng>[];
+      for (var i = expandedStart; i <= expandedEnd; i++) {
+        final sample = samples[i];
+        points.add(AppLatLng(sample.latitude!, sample.longitude!));
+      }
+
+      // The surrounding point guarantees two points for an isolated event
+      // while preserving a single continuous segment for adjacent events.
+      if (points.length >= 2) {
         polylines.add(AppPolyline(
           id: '${idPrefix}_$segmentIndex',
-          points: List<AppLatLng>.from(segment),
+          points: points,
           color: color,
           width: 7.0,
         ));
         segmentIndex++;
       }
-      segment = [];
     }
 
-    for (final sample in samples) {
-      final g = sample.longitudinalG ?? sample.accelX;
-      if (g != null && g.isFinite && predicate(g)) {
-        segment.add(AppLatLng(sample.latitude!, sample.longitude!));
+    for (var i = 1; i < eventIndices.length; i++) {
+      final index = eventIndices[i];
+      // Keep nearby threshold samples in one event run.  A gap of more than
+      // two samples starts a new visual event while allowing brief sensor
+      // dropouts inside a hard maneuver.
+      if (index - runEnd <= 2) {
+        runEnd = index;
       } else {
-        flush();
+        emitRun(runStart, runEnd);
+        runStart = runEnd = index;
       }
     }
-    flush();
+    emitRun(runStart, runEnd);
+
     return polylines;
   }