UTM 5.0.5 Beta causes bluetooth headphones to switch to headset mode when playing audio in VM

When running a VM in UTM 5.0.5 Beta, Bluetooth connected headphones (AirPods Max and AirPods tested) will swap to "headset" mode (brief audio interruption followed by lower quality audio) from their typical "headphones" mode (higher quality audio, no mic) any time audio is **played** in any app in the VM. This state persists as long as the VM is playing audio, followed by reverting to headphones mode after a second or two of the audio ceasing in the VM.

It acts like UTM 5.0.5 is looking for mic input even when it's exclusively outputting audio, the same way entering an audio chat channel in Discord causes Bluetooth headphones to automatically swap to headset mode.

This behavior does not occur in UTM 4.7.5 on the same host with the same guest OS.

I've even tried adjusting the privacy settings on the host to deny UTM 5.0.5 Beta's access to the mic to see if it would prevent the behavior, but it persists, even when something like a muted video ad on a webpage in the VM loads.

**Configuration**
* UTM Version: 5.0.5 Beta
* host macOS Version: 27.0
* guest OS: macOS 27.0
* Mac Chip (Intel, M1, ...): M1

Reproduce audio playback in a VM with UTM 5.0.5 Beta using the reported Bluetooth headphones, then compare the behavior with UTM 4.7.5 on the same host and guest setup. Trace the audio and microphone handling involved during playback; done means VM audio no longer switches the headphones to headset mode when no microphone input is used.

Written by the indexing model from the issue text.