Experiment: execute AAR validation through sealed executor

[mark-e-deyoung]

Bounded cross-project qualification rep; not intended to transfer AAR authority into Agent Dispatch.

This PR changes only the existing sealed-public-execution contract workflow on an experimental branch. It builds a public-safe AAR capsule containing the pinned AAR evidence-summary tool plus synthetic evidence fixtures, executes it through Agent Dispatch's existing sealed worker, decrypts the result, and verifies:

• assignment/result correlation;
• sealed-executor success;
• AAR task class aar.recovery.validate;
• authority_owner remains android-artifact-recovery;
• expected AAR claims and UNKNOWN preservation.

No new executor, queue, scheduler, secret, target authority, or production API is introduced. If the rep passes, retain the run/PR as evidence and close this PR unless the cross-project fixture separately earns permanent retention.

[mark-e-deyoung]

Qualification PASS.

Run: https://github.com/SemperSupra/agent-dispatch/actions/runs/35633947996

The existing sealed-public-execution worker successfully executed the pinned AAR aar.recovery.validate projection, preserved authority_owner=android-artifact-recovery, produced the expected AAR claims, preserved execution-environment as UNKNOWN, and completed the seal/decrypt round trip under assignment aar-golden-qualify-001.

The durable AAR-side finding is recorded in android-artifact-recovery-private/docs/findings/agent-dispatch-sealed-execution-qualification.md.

This experimental fixture does not earn permanent retention in Agent Dispatch main, so the PR can close unmerged; the run and PR remain the proving evidence.