Add uprated SOI taxable interest AGI targets

[MaxGhenis]

Summary

• activate SOI taxable-interest AGI-slice amount and return-count facts when Ledger has a same-scope all-income control to anchor the slice; if the control is newer, the slice is uprated, and if it is the latest available same-period control, the factor is 1
• annotate taxable-interest targets with the control source record, source period, target period, and factor, and drop slices when no all-income control exists
• classify all-income using both dimensions and AGI constraints so open-ended constrained rows like 500k_plus cannot be dropped as all-income controls
• strengthen the interest-distribution launch gate so broad state all-income totals alone no longer satisfy the by-AGI-bracket requirement

Context

The latest live Populace target diagnostics showed taxable-interest amount badly off while taxable-interest return counts and tax-exempt interest were close. The target surface had only broad taxable-interest amount controls, so the reweighter had little shape information for the taxable-interest tail.

Companion Ledger PR: PolicyEngine/arch-data#62 adds the missing SOI Historic Table 2 state-by-AGI taxable-interest return-count and amount facts from N00300/A00300, including explicit 500k_plus filters.

Tests

• uv run python -m pytest packages/populace-build/tests/test_us_fiscal_targets.py packages/populace-build/tests/test_us_fiscal_refresh_builder.py -q
• uv run ruff check packages/populace-build/src/populace/build/us_runtime/fiscal_targets.py packages/populace-build/tests/test_us_fiscal_targets.py
• uv run ruff format --check packages/populace-build/src/populace/build/us_runtime/fiscal_targets.py packages/populace-build/tests/test_us_fiscal_targets.py
• git diff --check