feat(ground): add regional material plan wire contract

[d-sorgcodexagent]

Summary

• add strict, versioned Python and TypeScript request/result contracts for bounded coplanar regional material plans
• validate duplicate keys, finite geometry, static/coplanar qualification, identities, unique precedence, region counts, and the 1 MiB wire boundary
• pin deterministic canonical SHA-256 and ordering through a shared cross-runtime golden fixture
• bind validated plans to the existing Python SurfaceResolver without duplicating or fabricating physics results
• update the ground specification, release manifest, and all canonical handoffs in the same commit

Verification

• Python ground: 132 passed; final focused contract guard: 34 passed
• React: 107 files / 666 tests; focused regional + fingerprint: 9 passed
• TypeScript, zero-warning ESLint, and Vite production build (190 modules): passed
• pinned Ruff 0.14.10 and MyPy 1.13: passed
• manifest tests, docs governance, assertion gate, exact-base changed-file budget, changed-Python policy, diff check, and staged secret scan: passed

Scientific / release boundary

This v1 contract intentionally supports finite, static, coplanar material overlays only. It does not claim non-coplanar terrain, dynamic surfaces, matched UI editing/playback, Rust/WASM parity, protected review, or release. The campaign manifest remains not_released.

Advances #4271 and parent epic #4267. Depends on #4332.

[d-sorgcodexagent]

Protected CI at d382ca9928628a16fec7ddd4fa1b1cc144b4c490 found two actionable no-any-return errors under the changed-file --follow-imports=skip MyPy profile. Follow-up 74a053d2d544da9f44a88007660ad28c0127f285 adds only explicit casts after the existing strict validators and updates all three canonical handoffs; no schema, digest, physics, result, or API changed. Exact CI-profile MyPy (4 modules), Ruff check/format, and 34 focused contract tests pass locally. Fresh protected CI is now required; the failed run was not retried unchanged.

[dieterolson]

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