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/bootstrap_cycle_test.go

@@ -51,7 +51,7 @@ func TestAModuleThatDoesNotProvideTheStoreStillBuilds(t *testing.T) {
 
 // A mapping that names an address still names the port, and the machine side is still the middle.
 //
-// The substrate bundle writes "127.0.0.1:5432:5432" today, so the shape is not hypothetical.
+// The foundation bundle writes "127.0.0.1:5432:5432" today, so the shape is not hypothetical.
 // Found in review: the first cut split on the first colon, read "127.0.0.1" as the machine port,
 // failed to parse it, and silently skipped the mapping — which put the filter back on the
 // declared port, the exact fault MachineSide was written to end.