- Add _haversine_km() great-circle distance function (pure Python, no PostGIS)
- EventListAPI now accepts optional latitude, longitude, radius_km params
- Bounding-box SQL pre-filter narrows candidates, Haversine filters precisely
- Progressive radius expansion: 10km → 25km → 50km → 100km if <6 results
- Backward compatible: falls back to pincode filtering when no coords provided
- Response includes radius_km field showing effective search radius used
- Guard radius_km float conversion against malformed input
- Use `is not None` checks for lat/lng (handles 0.0 edge case)
- Expansion list filters to only try radii larger than requested
Sicherhaven
9d61967350