distribution: the store's /v2/ checked over http through the front, beside the program's tool check (issue 1966)

A tool check alone is refused by the indexer's judge (ADR 0227 rule 8, ADR 0240 rule 2); the operator chose a check of
another kind on 2026-11-04.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

modules/distribution/internal/holder/holder_test.go

@@ -863,6 +863,11 @@ func TestTheHolderOfTheTwoImageSeats(t *testing.T) {
 				if ports, _ := r["ports"].([]any); len(ports) != 1 || ports[0] != "127.0.0.1:5001:5000" {
 					t.Errorf("the store's ports = %v, want the loopback only", r["ports"])
 				}
+				// The check of another kind beside the program's tool (ADR 0227 rule 8, ADR 0240 rule 2; the operator,
+				// 2026-11-04): the runtime asks the store's /v2/ through the program's front, its endpoint registry.
+				if h, _ := r["health"].(map[string]any); h["kind"] != "http" || h["endpoint"] != "registry" || h["path"] != "/v2/" {
+					t.Errorf("the store's health = %v, want http on the endpoint registry asking /v2/", r["health"])
+				}
 			case "program":
 				program = i
 				if h, _ := r["health"].(map[string]any); h["kind"] != "tool" || h["tool"] != "registry_health" {