Hold a joining build for a person without superseding its delivery, join only on an engine that keeps own groups, and keep a held module's settings (hq ADR 0328 §8, ADR 0334; re-review of 96e15f86)

A delivery does not send a joining build held for its library or its engine: the module waits for a person,
the plan stays open saying so and judges its other modules, and sends it once nothing holds it. A held move is
no move for the gate. A module joins only on an engine at contract 7, and a held module is composed with the
settings it last ran with. The runner's verdicts are said for their modules and judged by whether a move
changes them. mesh-host pinned at #97 (7a41e120), its bundle now examples/foundation-first-node.lock.

internal/catalogue/libraries_test.go

@@ -335,6 +335,7 @@ func TestTheEngineTakesWhatIsComposedForLibraries(t *testing.T) {
 	for _, node := range []string{"ace", "novox"} {
 		r := Resolution{Node: node, Account: "jochen", Modules: []Manifest{aRadarr(t), theRuntime(t)}}
 		with := librariesRendering()
+		with.RunnerJoinsOwnGroups = true // contract 7 (mesh-host #97): the runner on identities, setgid on own directories
 		with.Libraries["books"] = Library{Name: "books", Home: "ace", Root: "/storage/books", Reach: []string{"novox"}}
 		composed := composeLibraries(t, r, with)
 		body, err := json.Marshal(map[string]any{"declaration": validate.Version, "resources": composed.Resources,