fix: update Pastel UI environment variables format

Changed environment variable format from array to object syntax
for better Docker Compose compatibility:
- NEXT_PUBLIC_API_URL: https://pastel.kit.pivoine.art
- NEXT_PUBLIC_APP_URL: https://pastel.kit.pivoine.art

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

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

kit/compose.yaml

@@ -115,8 +115,8 @@ services:
     healthcheck:
       disable: true
     environment:
-      - NEXT_PUBLIC_API_URL=https://${KIT_PASTEL_TRAEFIK_HOST}
+      NEXT_PUBLIC_API_URL: https://${KIT_PASTEL_TRAEFIK_HOST}
-      - NEXT_PUBLIC_APP_URL=https://${KIT_PASTEL_TRAEFIK_HOST}
+      NEXT_PUBLIC_APP_URL: https://${KIT_PASTEL_TRAEFIK_HOST}
     networks:
       - compose_network
     labels: