feat: coordinate Types 0.7 contracts

[abrichr]

Summary

Combines the two compatible Types 0.7 contract slices on current main:

• Portable attended reconcile action and receipt invariants for uncertain delivery.
• Versioned public Execute v1 request, lifecycle, evidence receipt, signed webhook, and OpenAPI contracts.
• Regenerates the Execute OpenAPI artifact after reconciliation extends the imported attended schema.

This branch contains no Cloud implementation, tenant data, connector recipe, customer evidence, or deployment tuning.

Coordination

This draft supersedes the release composition of #19 and #20, but does not close either source PR. Do not merge or publish until the coordinated Types 0.7 / Flow 1.26 release is authorized.

Validation

• uv run pytest -q: 242 passed.
• Regenerated packaged schemas and confirmed no diff after generation.
• Built wheel and source distribution.
• scripts/check_source_boundary.py --require-dist passed for source tree and archives.