perf(ui): remove mirrored spectrum displays

- Simplifies UI by removing the duplicate spectrum displays
- Improves performance by reducing rendering workload during audio analysis
- Creates a cleaner, more streamlined progress visualization

Author: flexiondotorg

internal/ui/pass1.go

@@ -160,9 +160,6 @@ func (m *pass1Model) renderProgress() string {
 		s.WriteString("\n")
 		spectrum := renderSpectrum(m.lastUpdate.BarHeights, min(m.width-4, 76))
 		s.WriteString(spectrum)
-		s.WriteString("\n")
-		// Mirror for symmetry
-		s.WriteString(spectrum)
 		s.WriteString("\n\n")
 	}
 

internal/ui/pass2.go

@@ -218,8 +218,6 @@ func (m *pass2Model) renderProgress() string {
 		var leftCol strings.Builder
 		spectrum := renderSpectrum(m.lastUpdate.BarHeights, min(m.width-4, 72))
 		leftCol.WriteString(spectrum)
-		leftCol.WriteString("\n")
-		leftCol.WriteString(spectrum) // Mirror for stereo effect
 
 		var rightCol strings.Builder
 		if m.lastUpdate.FileSize > 0 || m.lastUpdate.VideoCodec != "" || m.lastUpdate.AudioCodec != "" {