fix: waveform fills viewport width when zoom is 1.0

Modified the waveform minWidth calculation to only apply when
zoom > 1, so the waveform fills the available viewport space
at default zoom level instead of creating unnecessary horizontal
scrolling.

Changes:
- minWidth only applied when zoom > 1
- At zoom = 1.0, waveform takes 100% of available space
- Scrollbar only appears when actually zoomed in

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/tracks/Track.tsx

@@ -729,7 +729,7 @@ export function Track({
         <div
           className="relative h-full"
           style={{
-            minWidth: track.audioBuffer ? `${duration * zoom * 100}px` : '100%'
+            minWidth: track.audioBuffer && zoom > 1 ? `${duration * zoom * 100}px` : '100%'
           }}
         >
         {/* Delete Button - Top Right Overlay */}