fix: remove CF label from crossfade hatch indicator

app.py

@@ -1776,15 +1776,6 @@ def _build_waveform_html(audio_path: str, segments: list, slot_id: str,
           ctx.stroke();
         }}
         ctx.restore();
-        // Label — centred on the join boundary line, straddling both segments
-        ctx.fillStyle = 'rgba(255,255,255,0.6)';
-        ctx.font = 'bold 9px sans-serif';
-        const cfW = xR - xL;
-        const label = '\u21C4 CF';   // ⇄ CF
-        const lw = ctx.measureText(label).width;
-        if (cfW > lw + 4) {{
-          ctx.fillText(label, xL + (cfW - lw) / 2, H - 3);
-        }}
       }}
     }}