fix: seek now auto-starts playback for intuitive interaction

Changed seek behavior to match user expectations:
- Clicking on waveform now immediately starts playing from that position
- Dragging timeline slider starts playback at the selected position
- No need to click Play button after seeking

Previous behavior:
- seek() only continued playback if music was already playing
- Otherwise it just set isPaused = true
- User had to seek AND THEN click play button

New behavior:
- seek() always starts playback automatically
- Click anywhere → music plays from that position
- Much more intuitive UX matching common audio editors

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

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

lib/audio/player.ts

@@ -114,22 +114,18 @@ export class AudioPlayer {
   }
 
   /**
-   * Seek to a specific time
+   * Seek to a specific time and start playback
    */
   async seek(time: number): Promise<void> {
     if (!this.audioBuffer) return;
 
-    const wasPlaying = this.isPlaying;
     const clampedTime = Math.max(0, Math.min(time, this.audioBuffer.duration));
 
     this.stop();
     this.pauseTime = clampedTime;
 
-    if (wasPlaying) {
+    // Always start playback after seeking
     await this.play(clampedTime);
-    } else {
-      this.isPaused = true;
-    }
   }
 
   /**