feat: add --device flag to sound play for output device selection

[SuaveIV]

Background

sound play currently opens the default system audio output via
DeviceSinkBuilder::open_default_sink() with no way to override it. The
rodio/experimental feature includes SpeakersBuilder and
available_outputs(), which expose device enumeration and selection along with
preferred sample rates, channel counts, and buffer sizes.

Proposed changes

• Add a --device flag to sound play accepting a device name string
• Add a sound devices command (or sound play --list-devices) that lists
  available output devices, marking the system default
• Route playback through SpeakersBuilder when --device is supplied, falling
  back to the existing default sink path when it is not

Motivation

Multi-output systems are a common case — routing to headphones vs speakers, a
USB DAC, or a specific ASIO device. This is one of the more frequently requested
audio player features and SpeakersBuilder gives us everything we need to
implement it without pulling in any new dependencies.

Notes

SpeakersBuilder is currently behind rodio/experimental, which is already
in the default feature set as of main.