Add Portable schema adapter

[drkwjr]

Summary

• Adds a small ma1a_portable_schema.yml adapter for the shared MA 1A / Portable schema.
• Keeps the existing Separation Agreement internals (users[0] and other_parties[0]) intact.
• Imports/exports canonical package-facing petitioner values through petitioners[0] and petitioners[1].
• Bridges children-of-marriage / children-subject-to-agreement booleans while keeping them separate from financial-statement household child fields.
• Wires the adapter into both current agreement entrypoint YAML files.

Why

This gives the combined 1A / Portable flow stable shared variable names without doing a risky repo-wide variable rename in the standalone interview.

Dependency

The current standalone Separation Agreement flow has a separate normal-walkthrough bug tracked in issue #3 and fixed in draft PR #4:

• Fix normal walkthrough after opposing-party address #3
• Fix Separation Agreement normal walkthrough #4

This adapter PR is intentionally scoped to schema/nomenclature alignment. Once PR #4 lands, this branch should be rebased and the full Separation Agreement walkthrough should be rerun without the workaround.

Validation

• python3 YAML parse across all question YAML files
• Embedded Python code: block syntax check with ast.parse
• git diff --check
• Local Docker before/after render smoke test against current origin/main and this branch for both entrypoints:
  • docassemble.ADivorceAgreement:divorceagreement.yml
  • docassemble.ADivorceAgreement:a_divorce_agreement.yml
  • /api/session/new returned 200 for both
  • first question render returned 200 for both
  • after submitting al_intro_screen=True and acknowledged_information_use=True, the next rendered screen matched baseline: A_Divorce_Agreement