raposza/tools: platform/raposza-canton/README.md

<!-- Copyright (c) 2026 bentzn --> <!-- SPDX-License-Identifier: Apache-2.0 --> # raposza-canton Everything that knows what Canton is: installations, versions, editions, configuration and overlays, node launching, PQS/scribe. Depends on `raposza-runtime`. Knows nothing about sandboxes: a class that