fix: Convert next.config.ts to JS to fix Netlify build

Netlify's build environment has a race condition where TypeScript is
auto-installed but not available when Next.js tries to transpile
next.config.ts. Using a plain JS config avoids this issue entirely.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: cj-vana

next.config.js

@@ -0,0 +1,6 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  /* config options here */
+};
+
+module.exports = nextConfig;