Refresh VOA council tax and official PIP target sources

[MaxGhenis]

Summary

• refresh the VOA council tax target source to the 2025 release and parse live England, Wales, and Scotland regional totals
• replace the PIP daily living target citation with the official January 2026 DWP statistics release
• align the target-registry checks with the refreshed 2025 target sources

Verification

• uvx ruff check policyengine_uk_data/targets/sources/dwp.py policyengine_uk_data/targets/sources/voa_council_tax.py policyengine_uk_data/tests/test_target_registry.py
• uv run pytest -q policyengine_uk_data/tests/test_target_registry.py policyengine_uk_data/tests/test_uc_by_children.py

Notes

• OBR March 2026, benefit cap November 2025, and the scaled local UC-by-children split were already on main; this PR closes the remaining freshness gaps from the audit.

[MaxGhenis]

Target-value update for this refresh:

PIP daily living

• dwp/pip_dl_standard_claimants: unchanged at 1,283,000
• dwp/pip_dl_enhanced_claimants: unchanged at 1,608,000
• change here is source quality, not the values: this PR switches those targets from a Disability Rights UK article to the official DWP January 2026 PIP statistics release

VOA council tax

• this PR moves the target year/source from the stored 2024 CSV to the live 2025 VOA publication, with Scotland refreshed from the 2025 Scottish chargeable-dwellings workbook
• headline effect on the regional .../total targets:

Region	2024 target	2025 target	Delta	% change
NORTH_EAST	1,280,700	1,287,830	+7,130	+0.56%
NORTH_WEST	3,441,730	3,466,140	+24,410	+0.71%
SOUTH_EAST	4,138,200	4,169,520	+31,320	+0.76%
SOUTH_WEST	2,683,030	2,704,390	+21,360	+0.80%
LONDON	3,813,790	3,837,430	+23,640	+0.62%
EAST_MIDLANDS	2,213,820	2,233,400	+19,580	+0.88%
WEST_MIDLANDS	2,619,300	2,637,190	+17,890	+0.68%
YORKSHIRE	2,530,680	2,547,080	+16,400	+0.65%
EAST_OF_ENGLAND	2,841,060	2,863,600	+22,540	+0.79%
WALES	1,476,690	1,484,410	+7,720	+0.52%
SCOTLAND	2,602,545	2,623,149	+20,604	+0.79%
TOTAL	29,641,545	29,854,139	+212,594	+0.72%

I am not listing all 99 band-level targets here, but the year-over-year movement is consistently modest and positive; the main point is that the targets are now coming from the latest official 2025 stock publications rather than the old baked-in 2024 CSV.