sia-server/configs/valid/mqtt-topic-prefix-max-characters.json, branch v0.2.0

sia-server/configs/valid/mqtt-topic-prefix-max-characters.json, branch v0.2.0 IoT backend server https://cgit.xengineering.eu/sia-server/atom?h=v0.2.0 2026-03-23T18:56:36Z Add test mqtt-topic-prefix-max-characters.json 2026-03-23T18:56:36Z xengineering me@xengineering.eu 2026-03-23T16:41:22Z urn:sha1:91844eb24c16d7ba768f913597702f8075fe8af2 This makes sure the maximum `mqtt/topic-prefix` string length is accepted.