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/two-node-db.yml

@@ -1,13 +1,13 @@
 # The DB-consumer chain a single node cannot host, proved across two machines.
 #
-# The app-postgres provider and the mesh's own substrate store both want host port 5432, so they
-# cannot share a machine — the collision that blocked this chain single-node. Here the substrate
+# The app-postgres provider and the mesh's own foundation store both want host port 5432, so they
+# cannot share a machine — the collision that blocked this chain single-node. Here the foundation
 # (store, broker, control) lives on `anchor` and NOTHING else; `laptop` runs the whole chain —
 # postgres and redis PROVIDERS plus the baserow and letta CONSUMERS that require them. Both
 # machines sit on one shared segment and enrol into the one mesh; only enrolment crosses to anchor,
 # over the underlay both machines already share. Provider and consumers are co-located on laptop, so
-# no cross-node module comms and no overlay are needed — and the 5432-vs-substrate conflict is gone
-# because the substrate store is on the OTHER node.
+# no cross-node module comms and no overlay are needed — and the 5432-vs-foundation conflict is gone
+# because the foundation store is on the OTHER node.
 scenario: two-node-db
 
 segments:
@@ -16,7 +16,7 @@ segments:
     cidr: [192.0.2.0/24]
 
 machines:
-  # The substrate ONLY: store, broker, control — three containers. Four gigabytes is plenty for a
+  # The foundation ONLY: store, broker, control — three containers. Four gigabytes is plenty for a
   # node that hosts no modules; the thrash the two-nodes bed warns of comes from stacking eleven
   # containers on a node, which this one never does.
   anchor:
@@ -43,7 +43,7 @@ machines:
     disk: 60GiB
 
 images:
-  - mesh-control:development
+  - mesh-controller:development
   # The per-module runtimes, built by scripts/build-module-runtime.sh and stocked here. Each carries
   # its module's provisioner, so no separate mesh-provision-* image is listed — the runtime is the
   # provisioner (ADR 0048).