feat(ground): add coplanar regional transitions

[d-sorgcodexagent]

Summary

• add bounded deterministic coplanar material overlays above the qualified skid/roll solver
• resolve overlap by unique precedence, split quadratic motion at exact material boundaries, and let finite base-domain exit win at a coincident edge
• preserve continuous linear/angular state while emitting strict surface_transition events plus an internal from/to identity ledger
• apply the active material to forces, path, and work accounting with typed event/step/transition limits
• keep Python/TypeScript result-event parsing in parity and update the canonical ground specification, campaign manifest, and all handoffs

Exact dependency

• Base branch: feat/4271-ground-skid-roll
• Reviewed base head: ee77b059bd83f7dafac7e0d411665231cdb7435c
• This is a normal child; no parent branch was rewritten or retargeted.

Verification

• python -m pytest src/shared/python/swing_sim/ground/tests -q — 121 passed (independently repeated on CPython 3.13)
• final focused regional/contract set — 38 passed
• React — 106 files / 662 tests; focused contract 5 passed
• TypeScript type-check, ESLint with zero warnings, and production build (189 modules)
• Ruff check/format and pinned MyPy 1.13 (28 ground modules + 12 isolated modules)
• release-manifest validator/tests, docs governance, changed-test assertions, diff check, and changed Python file-size budget

Honest boundary

This is a bounded #4271 slice, not issue closure. It intentionally does not claim changing normals/heights or surface velocity at boundaries, a versioned regional request/result wire schema, terrain deformation/grass/moisture calibration, torsional-spin damping, roll-to-skid, regional PyQt/React controls, compiled-runtime regional physics, UpstreamDrift parity, or protected release completion.

Closes no issue; advances #4271 under epic #4267.

[dieterolson]

Consolidated into #4409. Closing to reduce CI/CD runner load.