Add an audio source picker to the GUI so users can capture a specific
PipeWire device (sink monitor or microphone) instead of only the system
default output.
- vendor go2tv.app/screencast and patch the audio stream to accept a
target PipeWire node serial (PW_KEY_TARGET_OBJECT); the upstream lib
only ever auto-connected to the default
- capture: ListAudioSources enumerates PipeWire sinks/sources via pw-dump;
OpenPipeWire takes the selected node serial
- flinger/config/gui: AudioSource config field, persisted and exposed as
an Audio source dropdown (default output + enumerated devices)
Also fixes two pre-existing bugs surfaced by stop/start testing:
- engine Stop now waits for the video/audio/stats goroutines before
destroying the encoder (was a use-after-free SIGSEGV)
- Start/Stop now pause/resume the engine instead of tearing down and
re-opening the portal session, which the portal cannot reliably do
in-process (2nd CreateSession returned Ended/cancelled). Capture
session stays open across stop/start.
petere
3b3355e002