refactor: extract place-search and routing provider modules

server/providers/common/geo.js

@@ -0,0 +1,17 @@
+/**
+ * Haversine great-circle distance between two WGS-84 points.
+ *
+ * @param {number} lat1 - Latitude of point A (degrees).
+ * @param {number} lon1 - Longitude of point A (degrees).
+ * @param {number} lat2 - Latitude of point B (degrees).
+ * @param {number} lon2 - Longitude of point B (degrees).
+ * @returns {number} Distance in kilometers.
+ */
+export function haversineKm(lat1, lon1, lat2, lon2) {
+  const toRad = (value) => value * Math.PI / 180;
+  const dLat = toRad(lat2 - lat1);
+  const dLon = toRad(lon2 - lon1);
+  const a = Math.sin(dLat / 2) ** 2
+    + Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLon / 2) ** 2;
+  return 6371 * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+}