docs: document patched backend image + enterprise subscription patch

- CRACKED.md: target image is marker689/shuffle-backend-unchained:12082026
- docker-compose.yml: point backend at patched image (drop override file)
- shared.go: HandleCheckLicense also sets org.Subscriptions to an active
  Enterprise License so the UI shows 'Licensed' (was showing Unlicensed)
- gitignore shuffle-database runtime *.conf

Verified: backend image builds and runs with all limits lifted.

docker-compose.yml

@@ -14,7 +14,7 @@ services:
     depends_on:
       - backend
   backend:
-    image: ghcr.io/shuffle/shuffle-backend:latest
+    image: shuffle-backend-patched:test3
     container_name: shuffle-backend
     hostname: ${BACKEND_HOSTNAME}
     # Here for debugging: