Fix NY ESCC post-2024 to allow ITIN holders in baseline

[DTrim99]

Summary

This PR fixes a mistake in PR #7287 which incorrectly created a structural reform (S.9077) to add ITIN eligibility to the NY Empire State Child Credit starting in 2027.

The actual NY statute for the enhanced ESCC (2025-2028) already allows children with ITINs to qualify - this should have been in the baseline implementation, not a future reform.

Problem with PR #7287

PR #7287 made two errors:

1. Misidentified the issue as a future proposal - S.9077 was treated as proposed legislation when ITIN eligibility is already part of current law (2025-2028)
2. Left the baseline broken - The baseline ny_ctc_post_2024_eligible.py and ny_ctc_post_2024_base.py used ctc_qualifying_child which ties to federal SSN requirements (IRC 24(h)(7)), incorrectly excluding ITIN children

What This PR Does

1. Reverts S.9077 reform files - Removes the incorrectly created structural reform:

   • policyengine_us/parameters/gov/contrib/states/ny/s9077/
   • policyengine_us/reforms/states/ny/s9077/
   • policyengine_us/tests/policy/contrib/states/ny/s9077/

2. Fixes baseline NY ESCC logic - Updates eligibility to use has_itin (which covers both SSN and ITIN holders) instead of ctc_qualifying_child (SSN only):

   • ny_ctc_post_2024_eligible.py
   • ny_ctc_post_2024_base.py

3. Updates tests - Adds tests verifying ITIN children qualify in the baseline (not just with a reform)

Code Change

Before (broken):

qualifies_for_federal_ctc = person("ctc_qualifying_child", period)
qualifies = qualifies_for_federal_ctc & (age >= p.minimum_age)

After (fixed):

is_dependent = person("is_tax_unit_dependent", period)
has_valid_id = person("has_itin", period)  # has_itin includes SSN
age_eligible = age < p.post_2024.amount.thresholds[-1]
qualifies = is_dependent & has_valid_id & age_eligible & (age >= p.minimum_age)

Test Plan

• All NY CTC post-2024 eligible tests pass (17 tests)
• All NY CTC post-2024 base tests pass (20 tests)
• Tests verify ITIN children qualify in baseline

Closes #7322

---

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (67abb79) to head (901599b).
⚠️ Report is 33 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##             main     #7323       +/-   ##
============================================
+ Coverage   72.11%   100.00%   +27.88%     
============================================
  Files        3794         3     -3791     
  Lines       54662        54    -54608     
  Branches      275         1      -274     
============================================
- Hits        39418        54    -39364     
+ Misses      15228         0    -15228     
+ Partials       16         0       -16     

Flag	Coverage Δ
unittests	100.00% <100.00%> (+27.88%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[DTrim99]

Legal code from New York:

(D) For the purposes of this paragraph, a qualifying child shall be an
individual who: (i) is a child, sibling, or stepsibling of the taxpayer,
or a descendent of any such relative; (ii) has the same principal place
of abode as the taxpayer for more than one-half of the taxable year;
(iii) has not attained age seventeen; (iv) has not provided over
one-half of such individual's own support for the calendar year in which
the taxable year of the taxpayer begins; (v) has not filed a joint
return (other than only for a claim of refund) with the individual's
spouse under section six hundred fifty-one of this article for the
taxable year; and (vi) is a citizen or national of the United States, or
an individual with an individual taxpayer identification number issued
by the internal revenue service.