Add GET /api/routes/:routeId/export/google-maps and
GET /api/routes/:routeId/export/apple-maps. Builds native-navigation
deep-link URLs from the route's stops in optimized order (origin = first
stop, destination = last stop, the rest as ordered intermediate
waypoints). Validates per-platform waypoint limits (Google Maps ≤ 9,
Apple Maps ≤ 15) and returns { platform, url, stopCount, waypointCount }.
Auth: manager (any route) or groomer (own route only) via existing
/routes/* requireRole guard + resolveTargetStaffId.
- New pure-function service src/services/navigationExport.ts + 14 unit tests
- Updated UAT_PLAYBOOK.md §4.18 (navigation export test cases)
Co-Authored-By: Paperclip <noreply@paperclip.ing>