A directory the mesh places: ${dir:<id>} and the pathless directory resource

The first executable slice of ADR 0112 / to-be 27, sized to what the
operator settled tonight: a module definition names no host path for
its own data. A directory resource may omit path; composition resolves
it to <root>/<module>/<id>, the root a node's setting on Rendering with
/var/lib as the default — which reproduces exactly the layout novox
converged to by hand. ${dir:<id>} names the place from a resource's
path, content, mounts, environment and env-files, the same shape as
${bound:…}. A directory that states a path keeps it and still answers
by name — that is the adopted-data placement, mssql its live case.

Resolved in the controller at composition, so the wire format and the
host change not at all; a reference naming no directory refuses at the
manifest and again at composition; nested fills are rebuilt, never
written into the manifest's own maps, because one manifest composes
for many nodes.

internal/catalogue/manifest.go

@@ -1324,6 +1324,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	// Checked here rather than on the machine because the machine cannot tell the difference: by
 	// the time it sees the mount it is being asked to create the directory, which it can do.
 	problems = append(problems, m.undeclaredMounts()...)
+	problems = append(problems, m.unknownDirRefs()...)
 
 	for i, r := range m.Resources {
 		id, _ := r["id"].(string)