Add UK row-wise dataset cloning

[MaxGhenis]

Summary

• add a UK single-year dataset wrapper that clones person, benunit, and household tables with consistent ID remapping
• assign row-wise OA/LSOA/MSOA/LA/constituency/region geography to cloned households using the Populace-owned row-wise primitives
• validate person-household and person-benunit links after cloning and support writing a valid PolicyEngine-UK single-year H5
• export the dataset helper API and add PyTables to the UK extra because HDFStore is required for UK H5 read/write

Real Populace UK 2023 pilot

Using the current Populace UK 2023 H5 and the official crosswalk sources from #136:

• base shapes: person 1,157,100; benunit 618,980; household 535,080
• crosswalk coverage: 650/650 constituencies and 360/360 local authorities covered/sampleable
• n_clones=1: household weight preserved exactly; 0 blank geographies; 100% FRS region-code match; 650/650 constituencies and 360/360 LAs covered
• n_clones=2: household weight preserved exactly; 0 blank geographies; 100% FRS region-code match; 650/650 constituencies and 360/360 LAs covered
• weakest n_clones=2 constituency support: Na h-Eileanan an Iar, 555 rows/source households
• weakest n_clones=2 LA support: Isles of Scilly, 26 rows/source households; City of London, 80 rows/source households

Checks

• uv run --frozen --package populace-build --group dev python -m pytest packages/populace-build/tests/test_uk_rowwise_dataset.py packages/populace-build/tests/test_uk_rowwise_geography.py -q
• uv run --frozen --package populace-build --extra uk --group dev python -m pytest packages/populace-build/tests/test_uk_rowwise_dataset.py -q
• uv run --frozen --package populace-build --extra uk --group dev python -m pytest packages/populace-build/tests/test_uk_rowwise_dataset.py packages/populace-build/tests/test_uk_rowwise_geography.py packages/populace-build/tests/test_uk_geography_sources.py -q
• uv run --frozen ruff check .
• git diff --check
• uv run --frozen --all-packages --group dev python -m pytest -q
• env -u UV_FROZEN uv lock --check
• real Populace UK 2023 1x/2x pilot described above

Review cycle

• Read-only review found no actionable findings after inspecting the wrapper, tests, exports, dependency update, row-wise primitive contract, and installed UKSingleYearDataset H5/simulation loading contract.