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/co_located_test.go

@@ -62,7 +62,7 @@ func routeProxy() Manifest {
 // A co-located provider's served VALUES reach its consumer, not just its served keys.
 //
 // The mesh walks a provider on ANOTHER machine and settles what it serves with that node's settings
-// layers before offering it (cmd/mesh-control plan.go, theRestOfTheMesh). A provider on the
+// layers before offering it (cmd/mesh-controller plan.go, theRestOfTheMesh). A provider on the
 // consumer's own machine was never settled at all: resolve.go's servedHere and declaration.go's
 // here() both read the manifest and stop there. So a served value the operator supplied — the one
 // kind of value a manifest cannot carry, because it is different on every mesh — arrived as the