Add JSDoc documentation to all TypeScript files

packages/api-client/src/client.ts

@@ -1,3 +1,7 @@
+// ── API Client ──
+// Thin wrapper around the server-side API routes. Handles journey search,
+// geocoding, bike/walk routing, calendar fetching, and WienerLinien monitoring.
+
 import type {
   GeocodeResult,
   NearbyStop,
@@ -16,6 +20,11 @@ type SearchJourneyOptions = {
   arriveBy?: boolean;
 };
 
+/**
+ * Fallback window (2 hours) to search backwards when an arrive-by query
+ * returns no journeys. HAFAS sometimes fails to find connections if the
+ * target time is too tight.
+ */
 const ARRIVE_BY_FALLBACK_WINDOW_MS = 2 * 60 * 60 * 1000;
 
 function buildUrl(base: string, path: string, params: Record<string, string> = {}): string {
@@ -51,11 +60,19 @@ function buildTripSearchBody(
   };
 }
 
+/**
+ * Normalize HAFAS coordinates. HAFAS may return coordinates in either
+ * decimal degrees or micro-degrees (1e6 factor). This detects and fixes it.
+ */
 function normalizeHafasCoordinate(value: number | undefined): number | undefined {
   if (value == null) return undefined;
   return Math.abs(value) > 1000 ? value / 1e6 : value;
 }
 
+/**
+ * Client for the TimeToLeave server API. Proxy requests to HAFAS, OSRM,
+ * Nominatim, and WienerLinien backends. Set `baseUrl` to your deployed app.
+ */
 export class ApiClient {
   private readonly baseUrl: string;