fix: fix data race on micVolume field

micVolume was accessed from both the UI goroutine (SetMicVolume,
GetMicVolume) and the audio source goroutine (sourceRoutine) without
synchronization, a data race under the Go memory model.

Switch to atomic.Uint32 storing float32 bits to make reads and writes
safe across goroutines.

gumble/gumbleopenal/stream.go

@@ -3,8 +3,10 @@ package gumbleopenal
 import (
 	"encoding/binary"
 	"errors"
+	"math"
 	"os/exec"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"git.stormux.org/storm/barnard/audio"
@@ -60,7 +62,7 @@ type Stream struct {
 	sourceFormat    openal.Format
 	sourceChannels  int
 	sourceFrameSize int
-	micVolume       float32
+	micVolume       atomic.Uint32 // float32 stored as bits
 	sourceStop      chan bool
 
 	deviceSink  *openal.Device
@@ -110,7 +112,6 @@ func New(client *gumble.Client, inputDevice *string, outputDevice *string, test
 		sourceFormat:    inputFormat,
 		sourceChannels:  sourceChannels,
 		sourceFrameSize: frmsz,
-		micVolume:       1.0,
 		micAGC:          audio.NewAGC(), // Always enable AGC for outgoing mic
 	}
 	if sourceChannels == 2 {
@@ -209,7 +210,11 @@ func (s *Stream) StopSource() error {
 }
 
 func (s *Stream) GetMicVolume() float32 {
-	return s.micVolume
+	bits := s.micVolume.Load()
+	if bits == 0 {
+		return 1.0 // default on first access
+	}
+	return math.Float32frombits(bits)
 }
 
 func (s *Stream) SetMicVolume(change float32, relative bool) {
@@ -225,7 +230,7 @@ func (s *Stream) SetMicVolume(change float32, relative bool) {
 	if val <= 0 {
 		val = 0
 	}
-	s.micVolume = val
+	s.micVolume.Store(math.Float32bits(val))
 }
 
 func (s *Stream) OnAudioStream(e *gumble.AudioStreamEvent) {
@@ -417,8 +422,9 @@ func (s *Stream) sourceRoutine(inputDevice *string) {
 				hasMicInput = true
 				for i := 0; i < sampleCount; i++ {
 					sample := int16(binary.LittleEndian.Uint16(buff[i*2:]))
-					if s.micVolume != 1.0 {
-						sample = int16(float32(sample) * s.micVolume)
+					vol := s.GetMicVolume()
+					if vol != 1.0 {
+						sample = int16(float32(sample) * vol)
 					}
 					int16Buffer[i] = sample
 				}