v0.4.2

fix(connect): suppress transient audio_key_error during dealer reconnect

Account-side Spotify dealer-disconnect bursts produce a single audio-key
timeout log line per zone while spirc reconnects internally within
seconds. The log-observer surfaced that immediately as audio_key_error,
which tripped the per-zone cooldown in lox-audioserver and produced
~5 minutes of unplayable state per zone, multiple times per day.

Defer the audio_key_error emit by 5s and suppress it if a healthy
event (playing / position_correction) arrived in the meantime. A
permanent audio-key fault never produces a healthy event, so it still
surfaces after the grace window. Re-arm on suppression so a later
fault in the same session can still report.

Bumps version 0.4.1 -> 0.4.2. Refs lox-audioserver#252.