feat(interface): expose environment metadata

[drewstone]

Change

• expose detached provider-returned metadata on AgentEnvironment
• preserve a recursively frozen Sandbox metadata snapshot in the Tangle provider
• state explicitly that metadata is not authorization evidence

Proof

• Agent Interface: 415/415 tests, typecheck, build
• Tangle provider: 69/69 tests, typecheck, build
• changeset status: Interface and Tangle provider minor releases
• independent Luna review: APPROVE, 0 blockers

[tangletools]

✅ Auto-approved drewstone PR — 903b3716

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 · 2026-08-13T23:28:16Z}