Say the router's refusal of a proposal only once its discard is kept (issue 589)

The refusal test failed on a loaded build agent: Propose returned on hearing the
refusal before HeardEnd had written the discard, so a reader right after saw
nothing decided. The question path keeps the same order.

modules/claude-code/cmd/claude-code/proposals.go

@@ -838,14 +838,20 @@ func HeardEnd(p Paths, store ProposalStore, w asks.Warrant, now time.Time) (stri
 	if !known || (w.About != "" && w.About != prop.Ask().About) {
 		return "", nil
 	}
+	// Said to a proposer waiting on it only once the discard is kept: what it reads next is already there (the
+	// flake of the router's refusal test under a loaded build agent, 2026-10-12).
+	tell := func() {
 		endedMu.Lock()
 		ended[w.Ask] = w
 		endedMu.Unlock()
+	}
 	approved, err := ReadApproved(p)
 	if err != nil {
+		tell()
 		return "", err
 	}
 	if _, done := approved.Decided[w.Ask]; done {
+		tell()
 		return "", nil
 	}
 	// Heard, not read from a record: Reconcile still reads the router's record of it, so an ask the router took after
@@ -856,7 +862,9 @@ func HeardEnd(p Paths, store ProposalStore, w asks.Warrant, now time.Time) (stri
 	}
 	approved.Decided[w.Ask] = d
 	delete(approved.Refused, w.Ask)
-	if err := writeApproved(p, approved); err != nil {
+	err = writeApproved(p, approved)
+	tell()
+	if err != nil {
 		return "", err
 	}
 	return "proposal " + w.Ask + ": " + d.Outcome, nil