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

test/sdk.test.ts

@@ -106,7 +106,7 @@ test("modules can SERVE: a real async tool, loaded and invoked over the broker",
   const broker = memBroker();
   const stop = await serveTools(broker, {});
 
-  // Invoke it the way a caller (mesh-control's command API) would — over the broker, by module and
+  // Invoke it the way a caller (mesh-controller's command API) would — over the broker, by module and
   // tool, each served on its own key `demo.create_site` (novox/hq ADR 0047).
   const result = (await invokeTool(broker, "demo", "create_site", { domain: "my-app" })) as { snippet: string };
   assert.match(result.snippet, /data-website-id="site-123"/);