An older merge does not move a source

The forge announces what it finds merged, and an old merge surfacing late moved the recorded head
backwards and rebuilt everything built from that repository, once per old merge. A merge made
before the source was last seen is history; one that says nothing about when is taken as news.
The catalogue now carries when each source was last seen. The bus-records test follows #116:
a module's tools are every one under its own name.

internal/inventory/busrecords_test.go

@@ -86,9 +86,11 @@ func TestAnAssignedModuleBecomesAUserWithWhatItDeclared(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		// Its tools are every one under its own name — the list in the manifest is a person's
+		// vocabulary for asking, not the module's permission to answer.
 		if !granted(perms.Publish, "mesh.mod.shop.event.order.placed") ||
 			!granted(perms.Publish, "mesh.seat.telegram-sender.accept.send") ||
-			!granted(perms.Subscribe, "mesh.mod.shop.tool.price") {
+			!granted(perms.Subscribe, "mesh.mod.shop.tool.>") {
 			t.Fatalf("one.shop's authority is not what it declared: %+v", perms)
 		}
 	}