Fix Hawaii CDCC going negative with negative SE income

[PavelMakarchuk]

Summary

• Clamp min_earned to non-negative in hi_cdcc.py to prevent negative self-employment income from producing a negative credit (which adds tax instead of reducing it)
• Fix missing commas in reference tuples for hi_cdcc_min_head_spouse_earned and hi_cdcc_income_floor_eligible (implicit string concatenation → proper tuple)
• Add 3 test cases covering negative and zero earned income scenarios

Root Cause

When a spouse has negative SE income, hi_cdcc_min_head_spouse_earned returns a negative value. Then min_(dependent_care_benefits, negative_earnings) produces a negative min_earned, and rate × negative = negative credit.

Fix

# Before (bug):
min_earned = min_(hi_dependent_care_benefits, hi_cdcc_min_head_spouse_earned)

# After (fix):
min_earned = max_(0, min_(hi_dependent_care_benefits, hi_cdcc_min_head_spouse_earned))

Test plan

• All 33 existing HI CDCC tests pass
• 3 new test cases: negative earnings + zero expenses, negative earnings + positive expenses, zero earnings
• Verified against issue Hawaii CDCC (hi_cdcc) goes negative when spouse has negative self-employment income #7409 example: $0 credit instead of -$1,919.51

Closes #7409

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (f073b57) to head (1d467fe).
⚠️ Report is 126 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #7441   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files            4         3    -1     
  Lines           76        52   -24     
  Branches         1         0    -1     
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- Hits            76        52   -24     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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