Support multiple OSM files in web server #50
Description
Currently the web server only uses the first OSM file when multiple are specified. We should support loading and using multiple OSM files for broader coverage.
Currently in providers.py:
- Only the first OSM file is used for main providers
- Additional files are logged but ignored
- Users may want to combine multiple OSM extracts for larger coverage areas
Proposed solution:
- Load all specified OSM files
- Merge or chain the providers appropriately
- Update documentation to clarify multi-file behavior