Add ability to select distance unit

lib/components/calculator/route_summary_widget.dart

@@ -1,4 +1,6 @@
 import 'package:flutter/material.dart';
+import 'package:mileograph_flutter/services/distance_unit_service.dart';
+import 'package:provider/provider.dart';
 
 class RouteSummaryWidget extends StatelessWidget {
   final double distance;
@@ -12,13 +14,14 @@ class RouteSummaryWidget extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final distanceUnits = context.watch<DistanceUnitService>();
     return Padding(
       padding: const EdgeInsets.all(16),
       child: Row(
         children: [
           Expanded(
             child: Text(
-              "Total Distance: ${distance.toStringAsFixed(2)} mi",
+              "Total Distance: ${distanceUnits.format(distance, decimals: 2)}",
               style: Theme.of(context).textTheme.titleMedium,
             ),
           ),
@@ -48,6 +51,7 @@ class RouteDetailsView extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final distanceUnits = context.watch<DistanceUnitService>();
     final highlightColor = Theme.of(context).colorScheme.primary;
     final mutedColor = Theme.of(context).colorScheme.outlineVariant;
     return Column(
@@ -78,7 +82,9 @@ class RouteDetailsView extends StatelessWidget {
                       ? TextStyle(color: highlightColor, fontWeight: FontWeight.w600)
                       : null,
                 ),
-                trailing: Text("${costs[index].toStringAsFixed(2)} mi"),
+                trailing: Text(
+                  distanceUnits.format(costs[index], decimals: 2),
+                ),
               );
             },
           ),