Clean prepared cache

Cleans cache material for a prepared manifest. Use this to remove obsolete resolved artifacts while keeping cache management inside the supervisor API instead of deleting launcher files directly.

curl -X POST "https://example.com/cache:cleanup" \  -H "Content-Type: application/json" \  -d '{    "manifest": "string"  }'

{  "manifest": "string",  "deleted": [    "string"  ],  "missing": [    "string"  ],  "status": "string"}

{  "code": "string",  "message": "string"}