Consolidation cluster 10: nodata (long-tail epic #2424) #2434

Follow-up to epic #2424 / #2390. Cluster 10 of 16. Parallel-safe.

Likely 1-2 PRs. The 13 files have a clean read/write split, so a 1 PR vs 2 PR call comes down to review surface.

Scope

Consolidate nodata semantics, attrs, lifecycle, validation, and round-trip into one parametrised home each on the read and write sides.

Files to consolidate (13)

Sub-PR A: read-side -> extend read/test_nodata.py

• test_masked_nodata_attr_2092.py
• test_nodata_attr_aliases_1582.py
• test_nodata_lifecycle_attrs_2135.py
• test_nodata_lifecycle_parity_2211.py
• test_nodata_nan_int_1774.py
• test_nodata_no_extra_copy_1553.py
• test_nodata_semantics_split_1988.py
• test_helper_band_nodata_2210.py

Sub-PR B: write-side / validation -> extend write/test_basic.py or new write/test_nodata.py

• test_mask_nodata_kwarg_2052.py
• test_nodata_bool_rejection_1911.py
• test_nodata_int64_precision_1847.py
• test_nodata_out_of_range_1581.py
• test_nodata_validation_1973.py

Boundary

GPU nodata (test_gpu_nodata_1542.py, test_mask_nodata_gpu_vrt_2052.py, test_gpu_writer_nan_sentinel_1599.py) belongs to the GPU cluster.

Constraints

• Tests-only.
• Markers from _helpers/markers.py; make_minimal_tiff from _helpers/tiff_builders.py.
• Descriptive IDs (e.g. id="alias[GDAL_NODATA->nodata]", id="lifecycle[masked-then-write]").
• CLUSTER_AUDIT_NODATA.md deleted before merge.

Verification

pytest xrspatial/geotiff/tests/read/test_nodata.py xrspatial/geotiff/tests/write/ -v
pytest xrspatial/geotiff/tests/ -x -q

File count drops by 12 (13 deleted, 1 added if write-side becomes new file).