* fix(audio): filter unsafe virtual devices that crash capture
This is a defensive fix for #624 heap corruption seen when PortAudio opens PipeWire pseudo-devices such as DeepFilterNet, default, pipewire, paplay, monitor, null, dummy, or filter-chain sources. The root cause is not fully proven, but avoiding explicit capture from these unsafe virtual rows should keep dictation on real microphones while still allowing System Default through device_index=None.
If this still crashes with a physical microphone selected, please confirm with the exact physical device name and audio stack details so the capture path can be narrowed further.
Fixes#624
* fix(settings): sync audio device fallback with raw name restore
Address Bugbot review on #629: match legacy "(default)" saved names and
clear stale config/engine state when a filtered device falls back to
System Default.
* fix(audio): keep system default capture off pseudo device indices
Stop converting System Default to an explicit PortAudio index in the
mic test, and fall back to host default capture when every enumerated
input is filtered as unsafe.
* test(audio): expect system-default fallback on reconnect
* test(audio): cover system-default fallback paths for capture
