Geozone sync progress and admin maps

Adds live per-source synchronization progress for long-running imports, including real OurAirports download/import progress and paged Spain ENAIRE progress.
Keeps long synchronization jobs observable when the browser request times out, avoiding false “Failed to fetch” results after a successful server-side import.
Restores actual geozone polygons in large-country administration maps after the initial fit instead of leaving only a nationwide bounding box.
Adds a dedicated zoomable World Airports administration map with clustered airport points from zoom level 5.
Makes Delete all imported data remove both national geozones and worldwide airport data while preserving source configurations.