fix: upload permissions in Docker and improve file validation

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-entrypoint.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+set -e
+
+mkdir -p /app/public/uploads
+chown -R nextjs:nodejs /app/public/uploads
+
+cd /app
+
+exec su-exec nextjs sh -c "npx prisma db push --skip-generate && exec npm start"