Prevent recording/data loss on Docker container recreation by declaring persistent /nvr volume

[Copilot]

Containerized deployments could lose recordings and metadata if data paths were not persisted outside the container filesystem. This update makes persistence requirements explicit in both image definition and operator docs.

• Docker image persistence contract

  • Added an explicit Docker volume declaration for runtime state:

    RUN mkdir -p /nvr
    VOLUME ["/nvr"]

• Persistence guidance in docs

  • Updated recording.storage_path guidance to clarify that Docker deployments must mount persistent storage for the configured recording path (default under /nvr).
  • Strengthened Docker run section language to state that recordings + SQLite DB are lost when persistent mounts are omitted, and clarified behavior for custom storage paths outside /nvr.