feat(interface): carry requested interactions through Tangle turns

[drewstone]

Adds one strict shared per-turn interaction posture and carries it unchanged through the Tangle provider to Sandbox prompt options.

The posture is part of retained request identity, so a retry cannot silently change permission, question, or plan behavior. This replaces downstream compatibility casts with a publishable contract.

Proof:

• agent-interface tests: 419/419
• agent-provider-tangle tests: 131/131
• both package type checks passed
• full workspace build passed
• package and control artifact checks passed
• merge-tree against origin/main passed

[tangletools]

✅ Auto-approved drewstone PR — d7ce0017

This PR was opened by the trusted drewstone account.
The full PR reviewer audit still runs separately and will publish findings if it detects issues.

This approval is provisional. It rests on the audit running. If the audit cannot run — for example the CLI bridge rejects it — this approval is dismissed rather than left standing, so an unrun check never reads as a passing one.

_{tangletools · auto-approval · reason: drewstone_author · 2026-08-15T07:52:19Z}