Test build for no audio on some PCs (#1165)

This build is for players who have no sound at all on 3.0.0, with No default audio device available in user/last_run.log. It is not a final release.

What changes

• When Windows reports no default audio device and SDL gives no driver name, the game now tries DirectSound before it goes silent. Before, that fallback only ran when the driver was named WASAPI.
• Everything else is 3.0.0.

How to test

1. Copy your save folder first.
2. Extract spartanport-windows.zip into a new folder, so your current install stays as it is.
3. Start the game and check whether the intro and the gameplay have sound.
4. Reply on #1165 with sound or still silent, plus your user/last_run.log.

Validation

• The new audio test failed before the fix and passes after it, together with the existing WASAPI fallback, forced driver and total failure tests, and the downmix test (MSYS2 CLANG64, warnings as errors).
• Built and opened on a clean Windows runner by the release workflow.
• Not checked in game: we could not reproduce a PC with no default audio device.