Add SSA SSI Table 7.B1 source package

[MaxGhenis]

Summary

• add a validated SSA Annual Statistical Supplement 2025 Table 7.B1 source package for 2024 SSI recipients and payments
• emit All areas plus state/DC recipient-count and payment-amount facts by total, aged, blind, and disabled SSI category
• add the source-package alias and tests pinning package counts plus California disabled SSI values and U.S. total SSI payments

Validation

• uv run --extra dev ruff check arch/source_package.py tests/test_arch_source_package.py
• uv run --extra dev pytest -q tests/test_arch_source_package.py -k "ssa_ssi_table_7b1 or ssa_supplement"
• uv run --extra dev pytest -q tests/test_arch_source_package.py
• uv run --extra dev pytest -q tests/test_arch_bundle.py -k "source_package_count or ssa"
• uv run --extra dev arch validate-package packages/ssa/ssi_table_7b1_2024 --year 2024
• uv run --extra dev arch build-suite ssa-ssi-table-7b1-2024 --year 2024 --out /tmp/arch-ssa-ssi-7b1-2024-alias --replace

Microplex smoke check

The generated consumer_facts.jsonl loads through PolicyEngine/microplex-us#52 into 416 SSI targets, including California disabled recipients = 849,834 and U.S. total SSI payments = $63,079,493,000.

Source: https://www.ssa.gov/policy/docs/statcomps/supplement/2025/7b.html