feat: add OSRM road-snapping for GPS routes and mileage (#21)

Routes now follow actual roads instead of cutting through buildings:
- New OsrmService calls free OSRM Match API to snap GPS points to roads
- Position history endpoint accepts ?matched=true for road-snapped geometry
- Stats use OSRM road distance instead of Haversine crow-flies distance
- Frontend shows solid blue polylines for matched routes, dashed for raw
- Handles chunking (100 coord limit), rate limiting, graceful fallback
- Distance badge shows accurate road miles on route trails

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/hooks/useGps.ts

@@ -9,6 +9,7 @@ import type {
   EnrollmentResponse,
   MyGpsStatus,
   DeviceQrInfo,
+  LocationHistoryResponse,
 } from '@/types/gps';
 import toast from 'react-hot-toast';
 import { queryKeys } from '@/lib/query-keys';
@@ -125,19 +126,22 @@ export function useDriverLocation(driverId: string) {
 
 /**
  * Get driver location history (for route trail display)
+ * By default, requests road-snapped routes from OSRM map matching
  */
 export function useDriverLocationHistory(driverId: string | null, from?: string, to?: string) {
-  return useQuery<Array<{ latitude: number; longitude: number; speed: number; timestamp: Date }>>({
+  return useQuery({
     queryKey: ['gps', 'locations', driverId, 'history', from, to],
     queryFn: async () => {
       const params = new URLSearchParams();
       if (from) params.append('from', from);
       if (to) params.append('to', to);
+      params.append('matched', 'true'); // Request road-snapped route
       const { data } = await api.get(`/gps/locations/${driverId}/history?${params}`);
       return data;
     },
     enabled: !!driverId,
-    refetchInterval: 30000, // Refresh every 30 seconds
+    refetchInterval: 60000, // Match routes less frequently (60s) since OSRM has rate limits
+    staleTime: 30000, // Consider data fresh for 30s
   });
 }