push: the wait is the call's or the controller's setting push-wait, never a length in the code (issue 629)

The operator's rule: a wait is never hard-coded, at most a default is configured. The push verb takes `wait`; without it the controller's setting `push-wait` (module default 2m) applies; a setting that cannot be read waits for nothing, as a push did before, and says so.

cmd/mesh-controller/seatverbs_schema_test.go

@@ -146,8 +146,7 @@ func TestAnArgumentAVerbDoesNotDeclareIsRefused(t *testing.T) {
 // naming one beside behind is refused rather than one of the two guessed.
 func TestAPushIsOneMachineOrSaysItIsTheWholeMesh(t *testing.T) {
 	argv, err := argvFor("push", map[string]any{"node": "g1", "why": "w"})
-	// A named push waits for the machine's own answer, so the call says how it went (novox/hq issue 629).
-	if err != nil || strings.Join(argv, " ") != "push g1 --wait 2m0s --why w" {
+	if err != nil || strings.Join(argv, " ") != "push g1 --wait 0s --why w" {
 		t.Fatalf("a named push: %v %v", argv, err)
 	}
 	for _, args := range []map[string]any{{"why": "w"}, {"behind": "true", "why": "w"}} {