fix(admin): serve built SPA and include it in release builds

registerStaticSpa was never mounted, so production only exposed org-admin
APIs. Wire it after auth/API routes, fold admin:build into npm run build,
and install admin-web deps during deploy so admin-web/build ships with the
release for same-origin /admin/*.

hub/src/admin/static.ts

@@ -70,9 +70,9 @@ export async function registerStaticSpa(app: FastifyInstance): Promise<void> {
     }
   });
 
-  // SPA client-side route fallback. `/admin/login` is registered earlier as a
-  // static route and takes precedence; everything else under /admin/* serves
-  // the index so SvelteKit's client-side router can resolve the view.
+  // SPA client-side route fallback. Auth registers `/admin/login` first so it
+  // takes precedence; everything else under /admin/* serves the index so
+  // SvelteKit's client-side router can resolve the view.
   app.get("/admin", async (_request, reply) => {
     return reply.type("text/html; charset=utf-8").send(indexHtml);
   });