Suppress sensitive libgm trace logging

[Phloraxx]

Problem

libgm uses Trace/Debug logs for encoded HTTP/protobuf response bodies. The production zerolog passed to Google Messages had no minimum level, so protocol payloads could be retained in Docker logs.

Fix

• add gmessages.ProductionLogger, clamped to zerolog.InfoLevel;
• use it for both the live Google Messages manager and the manual pairing command;
• keep Info/Warn/Error lifecycle and failure logs;
• regression-test that fake sensitive Trace/Debug payloads are suppressed even when the caller supplies a Trace-level base logger.

This is intentionally independent of the Google reauthentication logic merged in PR #19.