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

src/repos.ts

@@ -23,6 +23,6 @@ export function repositories(env: NodeJS.ProcessEnv = process.env): Repositories
   const host = env["MESH_LAB_HOST_BINARY"];
   if (host) found["mesh-host"] = dirname(host);
   const modules = env["MESH_LAB_MODULES"];
-  if (modules) found["mesh-control"] = dirname(dirname(modules));
+  if (modules) found["mesh-controller"] = dirname(dirname(modules));
   return found;
 }