Admit live E2 from a value-safe custody receipt

WH-ENG-20260822-AUDIT-E2-02 projected and then aborted: admit-plane had no
receipt adapter, so the runner sent zero packets. Consume custody receipts
as handles only, keep unconnected admission fail-closed, and retire -02.

Assistant: grok
Assistant-Session: 01a02670-3345-76f2-a014-70fde8e2a2bb

src/whitehat_security/engagement.py

@@ -43,6 +43,10 @@ class Engagement:
             raise AuthorizationError(
                 "engagement window elapsed with no live run; identifier must not be reused"
             )
+        if self.raw.get("status") == "aborted":
+            raise AuthorizationError(
+                "engagement aborted without target evidence; identifier must not be reused"
+            )
         if self.raw.get("status") == "proposed":
             raise AuthorizationError(
                 "engagement is proposed; operator approval and owner acknowledgement are pending"