Refactor

[alpha-beta-soup]

Refactoring prompted by the addition of one more DGGS in an earlier PR. Various PEP changes, typo corrections, etc. included too. All tests pass.

Expanded tests to 63, up from 49. Added the following:

Test matrix holes (2 tests):

• test_rhp_no_bisection, test_geohash_no_bisection

Geometry type coverage (2 tests):

• test_h3_linestring — exercises the LineString branch end-to-end using se-island-contours.gpkg
• test_h3_point — exercises the Point branch using se-island-height-pts.gpkg

Output validation (6 tests):

• Hive partition dirs named with correct parent-res prefix
• Explicit --parent-res reflected in partition dir names
• --geo point / --geo polygon produce a geometry column
• --geo point carries valid GeoParquet metadata
• --keep-attributes retains source columns (Name_2018, LCDB_UID)

Error paths (4 tests):

• parent_res >= resolution raises ParentResolutionException
• --compact without --id_field raises IdFieldError
• Unknown DGGS key raises ValueError
• Second run without -o raises FileExistsError