Add jefe mecánico to client booking flow

Cliente now picks a jefe mecánico after choosing the service so the
calendar shows that specific jefe's availability. Each jefe has its own
configurable parallel slot capacity (replacing the global SLOTS_PARALELOS
= 5). Admins manage jefes from /admin/jefes; jefes log in to /jefe to
see their daily agenda.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/app/jefe/layout.tsx

@@ -0,0 +1,31 @@
+"use client";
+import { usePathname, useRouter } from "next/navigation";
+
+export default function JefeLayout({ children }: { children: React.ReactNode }) {
+  const pathname = usePathname();
+  const router = useRouter();
+
+  async function cerrarSesion() {
+    await fetch("/api/auth/jefe-logout", { method: "POST" });
+    router.push("/jefe");
+  }
+
+  if (pathname === "/jefe") return <>{children}</>;
+
+  return (
+    <div className="min-h-screen flex flex-col">
+      <div className="max-w-5xl mx-auto w-full px-4 flex-1 flex flex-col py-6 gap-4">
+        <div className="flex items-center justify-between gap-2">
+          <h1 className="text-lg font-semibold text-white">🔧 Mi agenda</h1>
+          <button
+            onClick={cerrarSesion}
+            className="text-sm text-gray-300 hover:text-red-300 transition px-3 py-1.5 rounded-lg hover:bg-white/10"
+          >
+            Cerrar sesión
+          </button>
+        </div>
+        <main className="flex-1">{children}</main>
+      </div>
+    </div>
+  );
+}