Add monthly Universal Credit element caseload sources

[juaristi22]

Summary

• Add monthly DWP Universal Credit caseload packages for the childcare, housing, LCWRA, and carer elements
• Replace the May-only family-type and number-of-children packages with April–December 2025 histories
• Register all six packages in Chronicle's source aliases and UK bundle
• Preserve publisher provenance, monthly periods, benefit-unit entities, and Great Britain geography

The six packages add 198 publisher-sourced facts. Chronicle does not annualize, reconcile, or otherwise transform the published values.

Testing

• All six validate-package checks passed
• All six build-suite checks passed
• 120 passed in the source-package regression suite
• 8 passed in the source-package alias-drift suite
• UK bundle registration and CLI tests passed
• Ruff formatting and lint checks passed
• git diff --check passed

Fixes #187

[vahid-ahmadi]

Automated review pass (Claude Code, low-effort single diff pass). One finding:

db/data/dwp/uc_childcare_element_march_2021_august_2025/manifest.yaml:9 — source_url has a doubled segment (...march-2021-to-to-august-2025.ods) that doesn't match the recorded filename / R2 key; any re-fetch or provenance check against this URL will 404.

Nothing else qualifies — the chronicle/bundle.py and chronicle/source_package.py changes are consistent registry edits, and the removed *_may_2025 package IDs are dropped from both files together with their manifests.

[juaristi22]

Addressed Vahid's review comment in c8bb280.

The GOV.UK attachment URL itself uses the to-to-august-2025.ods basename, so I aligned the manifest filename, checked-in ODS filename, and raw R2 key/URI to that official basename rather than changing source_url to the cleaned filename, which returns 404.

Verification:

• uv run --locked pytest tests/test_chronicle_source_package.py::test_dwp_uc_childcare_element_package_preserves_monthly_publisher_series
• uv run --locked chronicle validate-package dwp-uc-childcare-element-march-2021-august-2025 --year 2025
• Confirmed the GOV.UK source_url returns content with an HTTP 206 range request.
• Uploaded the aligned raw artifact to ledger-raw.

I skipped a full bundle rebuild because this only changes artifact provenance metadata and a checked-in filename.