fix: switch social-image API from edge to nodejs runtime

The edge bundle exceeds the 1MB size limit on Vercel's free plan.
Switching to nodejs runtime avoids this constraint.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: mabdullahabid

pages/api/social-image.tsx

@@ -17,7 +17,7 @@ import { mapImageUrl } from '@/lib/map-image-url'
 import { notion } from '@/lib/notion-api'
 import { type NotionPageInfo, type PageError } from '@/lib/types'
 
-export const runtime = 'edge'
+export const runtime = 'nodejs'
 
 export default async function OGImage(
   req: NextApiRequest,