Say every walk a verb keeps, and clear a stop from a walk that walks again

cancel, clear and rebuild kept a walk's end or restart without saying it, as plans stop, retry and
release-backlog did before them. The controller's run now says every save a verb makes on the bus, so the
next verb cannot lose a mark the same way. A stop is cleared when a walk is resumed, so one that fails again
ends failed and the search for its merge runs (review 21, ADR 0308, issue 532).

cmd/mesh-controller/push.go

@@ -249,7 +249,7 @@ func serve(ctx context.Context) (err error) {
 	// (novox/hq to-be 45 §9).
 	checkEvents = bus
 	// And every walk this controller keeps in a new state, for the delivery it walks (novox/hq ADR 0239).
-	inventory.PlanSaved = func(p inventory.Plan) { sayPlanMoved(ctx, bus, open.inventory, p) }
+	inventory.PlanSaved = func(_ *inventory.Inventory, p inventory.Plan) { sayPlanMoved(ctx, bus, open.inventory, p) }
 	if err := server.Checks(following{open}); err != nil {
 		return err
 	}