Bind positive autonomy proof to the assessment time #483

🤖 Generated by the Agentic Engineer

Problem

The offline assessment can recommend a candidate using a required report observed after the assessment that names its bundle. That report cannot establish the assessment's positive proof.

Proposal

Only count positive completion reports that were available at the bound assessment time, preserving independently known negative evidence.

Acceptance criteria

A later report prevents a candidate recommendation; equal/earlier valid reports remain usable and known contraction failures remain negative.

Reproduced offline against freshly fetched main using synthetic fixtures. No inspected source was executed and no provider experiment was launched. Size: S.

Part of #223.