docs(registry): report the witness fields instead of asserting the facts (#56)

The README and LIMITATIONS fix in trace-registry #70 did not reach this
page, which still said the grade is unsigned response metadata and that
there is no signed witness timestamp. Both are true of the September 7
capture and false the day a receipt carries either, so the page now points
at witness_time_established and grade_cryptographically_bound and says both
are false for that capture. Flagged by Steven Mih as the one line left that
would need a pass at deploy time.


Claude-Session: https://claude.ai/code/session_01CDzMWcn12dszchgrKfXzZY

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: imran-siddique

registry/index.html

@@ -152,7 +152,7 @@ <h3>A signed checkpoint commits to the history</h3>
   <span class="label">Independent witnesses</span>
   <h2>One checkpoint, one verified external receipt</h2>
   <p>Checkpoint 1's signing-body digest is included under a Merkle root signed by a separately operated witness. The returned receipt and two independently fetched copies agree; verification runs offline against an explicitly pinned witness key. This was demonstrated on September 7, 2026, ahead of the September 9 briefing.</p>
-  <p>The response reports <code>countersigned-observed</code>. That grade is unsigned response metadata. The receipt has no signed witness timestamp and does not certify registry continuity. It authenticates inclusion of the signing-body digest, with the registry signature checked separately.</p>
+  <p>The response reports <code>countersigned-observed</code>. Whether a receipt carries a witness time or a signed grade is a property of that receipt rather than of the profile, so the verifier reports <code>witness_time_established</code> and <code>grade_cryptographically_bound</code> instead of asserting either. Both are false for the September 7 capture. The receipt does not certify registry continuity. It authenticates inclusion of the signing-body digest, with the registry signature checked separately.</p>
   <p>No recurring witness submission, reciprocal witnessing, or second witness is claimed. Parallel independent witnesses remain a deployment choice; original records stay with their holders.</p>
   <a class="button" href="https://github.com/agentrust-io/trace-registry/tree/main/docs/evidence/witness-2026-09-07">Receipt, key provenance and offline verification</a>
 </section>