Backdate TANF non-cash BBCE parameters to FY2016 and fix CO bug

[hua7450]

Summary

Backdates 5 TANF non-cash (BBCE) parameter files from 2020-07-01 to 2015-10-01, enabling SNAP BBCE categorical eligibility simulations for years before 2020. Also fixes bugs where Colorado was incorrectly marked as non-BBCE and Mississippi was missing from cross-file entries during its BBCE period.

Note: Many states adopted BBCE well before 2015 (some as early as 2000). This PR uses 2015-10-01 (FY2016) as the floor to align with the SNAP allotment/deduction parameter coverage from PR #7851. Further backdating to actual adoption dates is possible using the ERS SNAP Policy Database.

Data Sources

• USDA ERS SNAP Policy Database — monthly state-by-state BBCE data 1996-2020 (download)
• SNAP Screener data — current net income test values, cross-validated against existing YAML
• 14th SNAP State Options Report (May 2018) — confirms BBCE adoption list
• USDA BBCE States Chart — current BBCE status (link)

Parameters Updated (5 files)

File	Changes
income_limit/gross.yaml	Push back to 2015-10-01 + 8 mid-period state changes; removed redundant CO 2022-11-30 entry
asset_limit.yaml	Push back to 2015-10-01 + IN, MI, LA, MS changes + CO fix; fixed broken reference URL; added missing period metadata
requires_all_for_hheod.yaml	Push back + WV change (all→any Jul 2018); added missing unit/period metadata
net_applies/hheod.yaml	Push back + IN (2018), LA (2020), MS (2015-2019) BBCE; added missing unit/period metadata
net_applies/non_hheod.yaml	Push back + IN (2018), LA (2020), MS (2015-2019) BBCE; added missing unit/period metadata

Mid-Period State Changes (from ERS database)

State	Date	Change
IL	Jan 2016	Gross income 130% → 165%
IN	Jan 2018	Adopted BBCE (130%, $5K asset limit, net test applies)
CO	Jun 2018	Gross income 130% → 200%
WV	Jul 2018	Gross income 130% → 200%, requires-all → any for HHEOD
MS	Jul 2019	Dropped BBCE entirely
MI	Dec 2019	Asset limit $5K → $15K
LA	Apr 2020	Adopted BBCE (130%, no asset limit, net test applies)
KY	May 2020	Gross income 130% → 200%

Bug Fixes

• CO was marked as -.inf (non-BBCE) at 2020-07-01 in both gross.yaml and asset_limit.yaml. ERS data shows CO had BBCE with 130% FPL gross income limit and no asset test since at least October 2015, increasing to 200% FPL in June 2018.
• MS was missing from asset_limit.yaml, hheod.yaml, and non_hheod.yaml during its BBCE period (Oct 2015 – Jul 2019). ERS data shows MS had BBCE with no asset limit and no net income test. Added consistent entries across all files.

Cleanup

• Removed redundant CO 2022-11-30 entries (same values as earlier dates, kept regulatory ref as comment)
• Removed outdated "May have changed" comments for CO
• Fixed broken asset_limit.yaml reference URL (dead .net CDN → FNS landing page)
• Added missing unit and period metadata fields across 4 files

Test plan

• Existing SNAP tests pass (251 passed locally)
• Microsimulation passes
• Spot-check: CO 2017 should have BBCE at 130% FPL
• Spot-check: IN 2017 should NOT have BBCE; IN 2019 should have BBCE at 130%
• Spot-check: MS 2018 should have BBCE at 130%; MS 2020 should NOT have BBCE

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.46%. Comparing base (9b5a10c) to head (941b142).
⚠️ Report is 284 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##              main    #7852       +/-   ##
============================================
- Coverage   100.00%   71.46%   -28.54%     
============================================
  Files            5     4099     +4094     
  Lines           91    59132    +59041     
  Branches         3      288      +285     
============================================
+ Hits            91    42257    +42166     
- Misses           0    16869    +16869     
- Partials         0        6        +6     

Flag	Coverage Δ
unittests	71.46% <ø> (-28.54%)	⬇️

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