ChannelSetEntity

The connected device's channel set, stored per-device (one row per Room database).

The channel set was historically a single global DataStore (channel_set.pb) while messages are per-device, so switching between devices rendered one device's messages against another device's channels — the same channel then appeared multiple times in the conversation list (#4623). Storing it here, in the per-device database, keeps it in lockstep with the messages it labels. The whole ChannelSet proto (settings + lora_config) is persisted as one row so semantics match the old whole-proto DataStore exactly.