Add exact geography loader seam

[anth-volk]

Fixes #757

This is PR 3a in the incremental local H5 migration stack.

What this PR does:

• adds policyengine_us_data/calibration/local_h5/geography_loader.py
• introduces a class-based CalibrationGeographyLoader as the internal owner of exact geography resolution
• supports saved geography_assignment.npz, package-backed geography when available, and legacy stacked_blocks.npy fallback
• keeps publish_local_area.load_calibration_geography(...) as a compatibility wrapper over the new seam
• adds focused unit tests for geography loading, mismatch failures, fallback behavior, and canonical geometry identity

What this PR does not do:

• no traceability bundle yet
• no scope fingerprinting yet
• no pipeline metadata changes yet
• no coordinator typed-request changes

Compatibility boundary:

• public geography helpers remain available
• artifact names remain unchanged
• existing publish entrypoints keep the same external behavior

Testing:

• python -m py_compile policyengine_us_data/calibration/local_h5/geography_loader.py policyengine_us_data/calibration/publish_local_area.py tests/unit/calibration/fixtures/test_local_h5_geography_loader.py tests/unit/calibration/test_local_h5_geography_loader.py
• ruff check --ignore E402 policyengine_us_data/calibration/local_h5/geography_loader.py policyengine_us_data/calibration/publish_local_area.py tests/unit/calibration/fixtures/test_local_h5_geography_loader.py tests/unit/calibration/test_local_h5_geography_loader.py
• python -m pytest --noconftest tests/unit/calibration/test_local_h5_geography_loader.py -q
• result: 5 passed

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Project	Deployment	Actions	Updated (UTC)
pipeline-diagrams	Error		Apr 14, 2026 9:05pm