Add MapViewDirections advanced routing — waypoints, modes, traffic, split routes

[jkasprzyk17]

Context

The core MapViewDirections component (#7) covers origin → destination routing. react-native-maps-directions also supports advanced Google Directions options that many production apps rely on: multi-stop routes, travel modes, traffic-aware ETAs, waypoint optimization, and automatic route splitting when waypoint limits are exceeded.

Reference props: https://github.com/bramus/react-native-maps-directions#props

Goal

Reach feature parity with react-native-maps-directions advanced routing props:

<MapViewDirections
  origin={origin}
  destination={destination}
  waypoints={stops}
  mode="DRIVING"
  language="pl"
  optimizeWaypoints
  splitWaypoints
  timePrecision="now"
  precision="high"
  resetOnChange={false}
  apiKey={GOOGLE_MAPS_APIKEY}
/>

Scope

• Waypoints — waypoints?: (Coordinate | string)[] between origin and destination.
• Travel mode — mode?: 'DRIVING' | 'BICYCLING' | 'WALKING' | 'TRANSIT' (default 'DRIVING').
• Language — language?: string (default 'en').
• Region bias — region?: string for string-based locations.
• Waypoint optimization — optimizeWaypoints?: boolean (document higher Google billing tier).
• Split waypoints — splitWaypoints?: boolean to bypass 10/25 waypoint limits by splitting into multiple API requests and merging polylines.
• Traffic / time — timePrecision?: 'none' | 'now' for realtime traffic duration.
• Polyline precision — precision?: 'high' | 'low':
  • high — full step-level polyline detail
  • low — overview polyline (smoothed, better performance)
• Reset behavior — resetOnChange?: boolean (default true); when false, keep previous polyline visible while refetching to avoid glitching.
• Channel — channel?: string for Google API reporting.
• Custom base URL — directionsServiceBaseUrl?: string (default Google JSON endpoint).
• Pass waypointOrder from API response through onReady.
• Pass fare object through onReady when returned (transit).
• Document billing implications for optimizeWaypoints, splitWaypoints, and timePrecision: 'now'.

Out of scope

• Flexible location string formats (address, place_id:) — Add MapViewDirections advanced routing — waypoints, modes, traffic, split routes #8 handles encoding; this issue consumes already-resolved or string values passed to Google API.
• Native MapKit routing — Add directions example, docs, and react-native-maps-directions migration guide #10.
• OSRM / GraphHopper backends.

Acceptance criteria

• Route with 2+ waypoints renders correctly.
• mode, language, and region are forwarded to the Directions API.
• optimizeWaypoints: true returns reordered waypointOrder in onReady.
• splitWaypoints: true handles >10 waypoints without API failure (multiple segments merged).
• timePrecision: 'now' affects duration when traffic data is available.
• precision: 'high' produces denser coordinate arrays than 'low'.
• resetOnChange: false avoids polyline flicker during refetch.
• Props and callback shapes match react-native-maps-directions documentation where applicable.
• Unit tests for waypoint splitting and query param construction.

Notes

Depends on #6 (package) and #7 (core fetch/render). Align prop names with react-native-maps-directions for easier migration (apikey alias optional).