feat(ground): define strict flight transfer contracts

[d-sorgcodexagent]

Summary

• define the strict versioned ground-transition request/result/event contract and canonical target-frame SI semantics
• fail closed on invalid frames, units, non-finite values, ordering, and unsupported model boundaries
• normally reconcile the ground parent with corrected wind carrier bb101cedd555d07d493aae998b46050c68660cdd without changing the PR base

Current evidence

• current head: 6a2bc9d06f6f9a28a0d615b19d2ed4fc13871059
• real Python 3.11: 89 tests passed
• real Python 3.10.20: 89 tests passed
• Ruff/format, pinned mypy 1.13, structural budgets, campaign manifest/parity tests, docs governance, assertions, ancestry, and diff checks pass locally

Release boundary

This is the strict ground-contract parent, not completed bounce/skid/roll physics or UI parity. Protected current-head CI, independent review, child-first #4288 integration, observer-to-wind propagation, and downstream release remain required.

Relates to #4268 and #4267.

[d-sorgcodexagent]

Exact-parent propagation update (2026-08-10):

• Published head: a93edb4bfd6a8dc9334122cd2ae660983d5bf424
• Merge parents, in order: prior strict-contract child e5bcbd1096d3be1f621a805c9d9f3fd321e375a5, quality-green repaired workflow 1e82f15026786ea0b08f78f4c001590ddce9ff39
• Branch/base preserved: feat/4268-ground-contract -> feat/4197-capability-observer
• Draft state preserved; no rebase, retarget, force-push, parent rewrite, or merge
• Conflict scope was limited to the four canonical handoff/spec files; no ground-contract production or test code conflicted
• Local evidence: all 46 strict ground-contract tests passed; documentation governance passed; changed-file size budget passed (0 violations); staged whitespace and conflict-marker checks passed
• Canonical handoffs and SPEC.md were updated in the same merge commit

Fresh exact-head protected CI is now required. Do not propagate this head into #4288 until the current quality gate is green; queued checks are not validation.

[d-sorgcodexagent]

Exact-head quality update: CI Standard quality-gate run 31434912350, job 93606770374, completed successfully for head a93edb4bfd6a8dc9334122cd2ae660983d5bf424. The broader rollup remains pending on queued runner-backed checks and there is still no approval, so this is not a merge or release claim.

[dieterolson]

Consolidated into #4409. Closing to eliminate CI runner load.