fix: use NODE_ENV for basePath to avoid runtime process error

The previous approach using process.env?.NEXT_PUBLIC_DEV_ENV causes
"process is not defined" in the browser. NODE_ENV is inlined at build
time by Next.js, avoiding the runtime error.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vmelikyan

src/theme.config.tsx

@@ -25,8 +25,7 @@ import { Separator } from "@/components/ui/separator";
 import { Code } from "@/components";
 import Image from "next/image";
 
-const isLocal = process.env?.NEXT_PUBLIC_DEV_ENV === "local";
-const basePath = !isLocal ? "/lifecycle-docs" : "";
+const basePath = process.env.NODE_ENV === "production" ? "/lifecycle-docs" : "";
 
 const logo = (
   <div className="flex items-center gap-2 logo-shake">