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

scenarios/first-node.yml

@@ -1,4 +1,4 @@
-# One machine, raising a substrate from the bundle its host carries.
+# One machine, raising a foundation from the bundle its host carries.
 #
 # This is the bootstrap class (novox/hq ADR 0009): no forge, no control plane to talk to, no
 # delivery. It exists to develop the steps of raising a mesh on a machine that has nothing but a
@@ -24,7 +24,7 @@ machines:
 # is what pinning asks for (novox/hq ADR 0006). The store and the broker are ordinary third-party
 # images, and the machine pulls them from the internet like anything else.
 images:
-  - mesh-control:development
+  - mesh-controller:development
 
 place:
   all: [host, runtime]