feat(distance): add Distance API support (#21)

* feat(distance): add Distance API support

Add full Distance API support matching the PHP SDK implementation:

- Add Coordinate class for flexible coordinate input formats (string, tuple, dict)
- Add distance() method for single origin to multiple destinations (GET)
- Add distance_matrix() method for multiple origins × destinations (POST)
- Add async job methods for large distance matrix calculations:
  - create_distance_matrix_job()
  - distance_matrix_job_status()
  - distance_matrix_jobs()
  - get_distance_matrix_job_results()
  - download_distance_matrix_job()
  - delete_distance_matrix_job()
- Enhance geocode() and reverse() with distance parameters
- Add type-safe constants for mode, units, ordering, and sorting
- Add verify_ssl parameter to client for testing with self-signed certs
- Add comprehensive unit tests and E2E tests
- Update README with full Distance API documentation

All changes are backward compatible - existing code continues to work.

* fix(tests): add __init__.py to test subdirectories

Prevents pytest module name collision between unit and e2e test files
with the same name (e.g., test_distance.py in both directories).

* fix(tests): correct distance API test assertion for origin ID

The API does not return origin ID for GET /distance requests, only
destination IDs. Updated test to verify destination IDs instead.

* fix(distance): remove unused f-string prefixes

* chore: prepare release v0.5.0

- Bump version to 0.5.0
- Update CHANGELOG with Distance API features

---------

Co-authored-by: Mathias Hansen <me@codemonkey.io>

Author: sylvesterdamgaard

CHANGELOG.md

@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.5.0] - 2026-01-06
+
+### Added
+- **Distance API support** with new methods for calculating distances between coordinates:
+  - `distance()` - Calculate distances from a single origin to multiple destinations
+  - `distance_matrix()` - Calculate distances from multiple origins to multiple destinations
+  - Support for `straightline` (haversine) and `driving` distance modes
+  - Support for `miles` and `km` units
+  - Optional sorting by distance or duration
+- New `Coordinate` class for representing geographic coordinates with optional IDs
+- Distance parameters for `geocode()` and `reverse()` methods to calculate distances inline
+- Comprehensive type definitions: `DistanceResponse`, `DistanceMatrixResponse`, `DistanceOrigin`, `DistanceDestination`
+- Distance mode constants: `DISTANCE_MODE_STRAIGHTLINE`, `DISTANCE_MODE_DRIVING`
+- Distance unit constants: `DISTANCE_UNITS_MILES`, `DISTANCE_UNITS_KM`
+
 ## [0.2.0] - 2025-08-08
 
 ### Changed
@@ -39,6 +54,7 @@ When ready to release:
 5. Push tags: `git push --tags`
 6. GitHub Actions will automatically publish to PyPI
 
-[Unreleased]: https://github.com/Geocodio/geocodio-library-python/compare/v0.2.0...HEAD
+[Unreleased]: https://github.com/Geocodio/geocodio-library-python/compare/v0.5.0...HEAD
+[0.5.0]: https://github.com/Geocodio/geocodio-library-python/compare/v0.4.0...v0.5.0
 [0.2.0]: https://github.com/Geocodio/geocodio-library-python/compare/v0.1.0...v0.2.0
 [0.1.0]: https://github.com/Geocodio/geocodio-library-python/releases/tag/v0.1.0