fix(audio): don't treat AppLifecycleState.inactive as backgrounded

inactive is a transient state — on Android it fires during MQTT push wake-up,
system dialogs, and app-switcher previews while the app is still visible. By
flipping _isBackgrounded=true on inactive, the auto-play gate in
_handleIncomingVoice silently skipped incoming voice messages on Android even
when the user was viewing the matching session. Only paused/detached should
mark backgrounded; leave inactive alone so the real edge governs.

lib/services/audio_service.dart

diff | view | blame | history