Replaces distance-based clustering with route-membership grouping:
- download_osm.py: collect route_refs per stop node; use platform roles
for bus stops, stop roles for rail stops
- prepare.py: carry route_refs through to master.gpkg
- render.py: group_by_route_membership() uses union-find to cluster
same-name stops sharing at least one route into one marker; stops on
disjoint routes are kept separate. No distance threshold needed.
Results: 786 bus platforms -> 465 markers (was 1610 -> 781).
Veksøvej: 2 platforms sharing routes 2A+5C -> 1 marker.
Peter Bangs Vej: 7 platforms on routes 10/21/22/4A/7A -> 2 markers.
marvin
54708e6cb3