v0.7.9 — debug logs that fit the message

A small fix with an outsized effect on how this project gets its information.

The raw MQTT debug line was trimmed at 400 characters — shorter than the messages it exists to show. The reporter on #2 sent a log to answer a question about which state keys a deviceStateCallback carries, and the state keys were exactly the part that had been cut off. Every protocol question this project has answered was answered from one of these logs.

The limit is now 2000 characters, which keeps a callback (~600) and a command reply with its base64 frame (~900) whole. Anything genuinely longer is still trimmed, but now says how many characters it dropped instead of ending mid-word and looking like the message itself was malformed.

If you have been asked for a debug log, this is the version to capture it on.

Unchanged

Nothing else. No frame, transport, state or service changes.