Medicaid medically needy: fix the pregnant, child and parent category flags against KFF and state sources #10473

Problem

In policyengine_us/parameters/gov/hhs/medicaid/eligibility/categories/medically_needy/categories/, the medically needy flags for pregnant women, children and parents don't match the KFF tables the files cite.

• pregnant.yaml and child/child.yaml: the same five state pairs are swapped as in the senior and disabled flags. AZ, ID, IN, NM and NV are on; AR, IL, IA, NJ and ND are off. KFF Appendix Table 3 (2018) lists AR, IL, IA, NJ and ND as running a medically needy program, and AZ, ID, IN, NM and NV under "NO PROGRAM".
• parent.yaml: the same five pairs, plus:
  • MA, VA and WI are on, though KFF lists CT, HI, MA, TN, TX, VA, WA and WI as having no medically needy parent group;
  • ME, VT and WV are off.
• 2026: check each file against KFF's 2026 tables and state sources for changes since 2018.

#10374 fixes the senior and disabled flags for these ten states, which is the aged, blind and disabled scope. It leaves these three files alone.

Effect

The flags that are on in AZ, ID, IN, NM and NV change no result, because those states' income limits are -.inf. The flags that are off remove a medically needy pathway from pregnant women, children and parents in AR, IA, IL, ND and NJ, and from parents in ME, VT and WV. That only matters once those groups' limits are modeled.

Proposed work

• Set each flag from KFF 2018 and 2026 and a state source, with dates where a state added or dropped a group.
• Check that each state switched on has a matching income and asset limit for the group.
• Add one YAML case per changed group.

Related

• Update Medicaid medically needy limits and switch on AR, IA, IL, NJ and ND #10374 (senior and disabled flags).
• Count blind people and use the individual or couple in the Medicaid medically needy test #10370 (medically needy financial unit).