Cover degenerate shape + NaN/Inf reads on GPU and dask geotiff backends (#1630)

Author: brendancol

.claude/sweep-test-coverage-state.csv

@@ -1,3 +1,3 @@
 module,last_inspected,issue,severity_max,categories_found,notes
-geotiff,2026-05-11,,MEDIUM,1;4,"Sweep 4 (2026-05-11 r4): added test_kwarg_coverage_2026_05_11_r4.py closing read_geotiff_gpu(name=) + read_geotiff_gpu(chunks=, name=) (Cat 4, dask+cupy backend), read_geotiff_dask(name=) (Cat 4), read_geotiff_gpu(max_pixels=) accept/reject + chunks+max_pixels reject (Cat 4), and open_geotiff(chunks=, name=) / open_geotiff(gpu=True, name=) / open_geotiff(gpu=True, chunks=, name=) / open_geotiff(gpu=True, max_pixels=) dispatch coverage. 12 tests, all passing on GPU host. Pass 3 (r3) added test_vrt_backend_coverage_2026_05_11.py covering read_vrt gpu/chunks/dtype/name (11 tests). No HIGH gaps remain."
+geotiff,2026-05-11,,HIGH,2;3,"Pass 5 (2026-05-11): added test_degenerate_shapes_backends_2026_05_11.py covering Cat 3 HIGH geometric gaps (1x1 / 1xN / Nx1 reads on dask+numpy, GPU, dask+cupy backends; 1x1 / 1xN / Nx1 writes through write_geotiff_gpu) and Cat 2 MEDIUM NaN/Inf gaps (all-NaN read on GPU + dask+cupy, Inf / -Inf reads on all non-eager backends, NaN sentinel mask on dask read path including sentinel block split across chunk boundary). 23 tests, all passing on GPU host. Prior passes still hold: pass 4 (r4) closed read_geotiff_gpu/dask name= + max_pixels= kwargs (Cat 4), pass 3 (r3) closed read_vrt GPU/dask+GPU backend dispatch (Cat 1) and dtype/name kwargs (Cat 4)."
 reproject,2026-05-10,,HIGH,1;4;5,"Added 39 tests: LiteCRS direct coverage, itrf_transform behaviour/roundtrip/array, itrf_frames, geoid_height numerical correctness + raster happy-path, vertical helpers (ellipsoidal<->orthometric/depth), reproject() lat/lon and latitude/longitude dim propagation. Note: _merge_arrays_cupy is imported but unused (no cupy merge dispatch in merge()); flagged as feature gap not test gap."