[GH-3147] Implement distributed GeoPandas skew

[jiayuasu]

What changed

• Add GeoSeries.skew and active-geometry delegation from GeoDataFrame.
• Express x/y shearing as a distributed ST_Affine operation with per-row center or centroid origins.
• Support degree and radian angles, 2D/3D tuple and Shapely Point origins, exact near-zero tangent handling, and unchanged Z coordinates.
• Share operation-wide numeric scalar validation across affine_transform, scale, and skew.
• Add direct regression tests and GeoPandas parity coverage across 2D and 3D geometry families.

Why

This implements #3147 without materializing geometry rows on the Spark driver. Sedona has no dedicated skew function, while ST_Affine can represent the GeoPandas shear matrix and its per-row origin offsets directly.

Validation

• 27 passed in the focused skew suite.
• 60 passed across the affected affine_transform, scale, and skew suites.
• Repository checks pass for all four changed Python files.

Part of #2230.
Closes #3147.

CC @petern48

[Copilot]

Pull request overview

Implements distributed GeoPandas-compatible skew for Sedona’s Spark GeoPandas layer by expressing shearing via ST_Affine, while sharing affine-family scalar validation and adding regression/parity tests.

Changes:

• Added GeoSeries.skew (with per-row "center"/"centroid" origins and explicit tuple/Point origins) implemented as a distributed ST_Affine operation.
• Refactored affine-family scalar normalization into a shared helper and reused it in affine_transform and scale.
• Added unit/regression tests plus GeoPandas parity coverage for skew across geometry families, origins, degrees/radians, and 3D Z preservation.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
python/sedona/spark/geopandas/geoseries.py	Adds _normalize_affine_scalar, refactors affine/scale validation, and implements distributed GeoSeries.skew via ST_Affine.
python/sedona/spark/geopandas/base.py	Adds GeoFrame.skew delegation (enables GeoDataFrame active-geometry delegation) and public docstring.
python/tests/geopandas/test_geoseries.py	Adds direct skew regression tests for angles/units, origins, metadata preservation, and delegation.
python/tests/geopandas/test_match_geopandas_series.py	Adds GeoPandas parity tests for skew (2D, radians, and 3D Z preservation).

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