- introduce LocationPickerScreen with flutter_map for selecting and confirming
locations, including markers and loading states
- integrate manual location editing in ReviewScreen and persist updated
coordinates/address in the report
- add GeocodingService with Nominatim search, Photon fallback, reverse
geocoding, debounced queries, caching, and timeouts
- update i18n (en) with new map/location strings; remove unused onboarding
and welcome texts