Rename mesh-control -> mesh-controller, substrate -> foundation

One name per thing, per the HQ glossary: the module/container/image/binary/repo
becomes mesh-controller, the seat the-controller, and the store+broker pair the
foundation (embedded base bundles, default template and example lock renamed with
their go:embed directives). No behaviour change — a pure vocabulary rename.

Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx

internal/catalogue/manifest.go

@@ -706,7 +706,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	// that provides the store and also builds something asks the mesh to put an artifact into the
 	// thing that artifact is needed to create.
 	//
-	// It is the question the substrate record asks of every candidate — can it grant itself the
+	// It is the question the foundation record asks of every candidate — can it grant itself the
 	// thing it provides? The store cannot create its own database, the broker cannot create its
 	// own virtual host, and a registry cannot grant itself a repository. Such a module names its
 	// image, exactly as the bundle names the three a first node starts from.