Hold or release a package

Create a notice on a package to hold or release it. Send `action: "hold"` to hold the package at the warehouse, or `action: "release"` to release it for delivery. Internally, `hold` is recorded as a warning notice and `release` is recorded as an info notice. Each call records a Notice for audit trail and updates the package's hold instruction accordingly. The response returns only the notice action result, not the full package payload.