mesh-knowledge: keep when an owed review is due, say it in the history, and tell the operator once after its last try (hq issue 497)

A failed review's try count was already kept with the version, but not when it was asked again, so a 10-minute
pause read as a review lost to a restart; and after the last try only the history and the health said so.

modules/mesh-knowledge/cmd/mesh-knowledge/store.go

@@ -63,7 +63,8 @@ type Store interface {
 	// SetFindings replaces the whole-set findings; Findings reads them.
 	SetFindings(ctx context.Context, f []Finding) error
 	Findings(ctx context.Context) ([]Finding, error)
-	// Told records that the operator was told about a topic's clauses, once; false when it was already.
+	// Told records that the operator was told of something, once, by its key: a topic's clauses drafted, or a
+	// version that ran out of review tries (novox/hq issue 497); false when it was already.
 	Told(ctx context.Context, topic string) (bool, error)
 }