fix(docker): remove runtime NEXT_PUBLIC_SUPABASE_URL override

NEXT_PUBLIC_ vars are baked into the Next.js bundle at build time.
Setting them at runtime with Docker-internal URLs (http://supabase-kong:8000)
causes SSR to fail with 500 because RSC uses the runtime value which
is unreachable from the browser. Let the build-time value
(https://myeasycms.frontieralgorithmics.de) be used everywhere.

docker-compose.yml

@@ -321,9 +321,8 @@ services:
     environment:
       NODE_ENV: production
       NEXT_PUBLIC_SITE_URL: ${SITE_URL:-http://localhost:3000}
-      # Server-side Supabase URL — direct Docker network access to Kong
-      NEXT_PUBLIC_SUPABASE_URL: http://supabase-kong:8000
-      NEXT_PUBLIC_SUPABASE_PUBLIC_KEY: ${SUPABASE_ANON_KEY}
+      # NEXT_PUBLIC_ vars are baked at build time — runtime values only apply
+      # to middleware/API routes. Don't override with Docker-internal URLs.
       SUPABASE_SECRET_KEY: ${SUPABASE_SERVICE_ROLE_KEY}
       SUPABASE_DB_WEBHOOK_SECRET: ${DB_WEBHOOK_SECRET:-webhooksecret}
       EMAIL_SENDER: ${EMAIL_SENDER:-noreply@myeasycms.de}