fix: add missing @supabase/ssr dependency

The migration commit referenced @supabase/ssr but didn't include it
in package.json.

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

Author: catomean

package-lock.json

@@ -27,6 +27,7 @@
     "@mdx-js/react": "^3.1.0",
     "@next/mdx": "^15.1.6",
     "@supabase/auth-helpers-nextjs": "^0.10.0",
+    "@supabase/ssr": "^0.8.0",
     "@supabase/supabase-js": "^2.47.10",
     "@tailwindcss/forms": "^0.5.7",
     "@tailwindcss/typography": "^0.5.16",