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/main.go

@@ -63,6 +63,15 @@ func run() error {
 	// 45 §6), so the next controller takes it at once rather than after its age.
 	defer theLease.release()
 
+	// Every walk a verb keeps is said on the bus, whichever verb kept it (novox/hq ADR 0308 decision 1): the save
+	// that starts or ends a walk keeps its mark, and no later save says it again. The serving controller says its
+	// own saves.
+	if args[0] != "serve" {
+		said, done := sayingWhatAVerbKept(ctx)
+		inventory.PlanSaved = said
+		defer done()
+	}
+
 	switch args[0] {
 	case "build":
 		return buildCommand(ctx, args[1:])