Add --bit-index, --string-length, and --string-byte-order options to SubscribeCommand, mirroring ReadCommand, and pass them into ModbusTagDefinition so that BitInRegister and String type subscriptions use the correct bit index and string length rather than silently defaulting to bit-0 / zero-length. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>