XY-860: Implement Decodex-native research/design runner and loop compiler

[yvette-carlisle]

Summary

• Add a Decodex-native research/design compiler that persists ambiguous intake as latent Decision Contracts.
• Add compile/promote CLI boundaries, Decision Contract schema extensions, and tests for readiness outcomes and unaccepted execution refusal.
• Update runtime/operator docs and Decodex skill guidance to supersede external research artifacts for Decodex runtime authority.

Validation

• cargo make fmt
• cargo make lint-fix
• cargo make test: 1001 tests run, 1001 passed, 1 skipped
• git diff --check