fix: remove overflow-hidden wrapper causing canvas width mismatch

Div wrapper with overflow-hidden clipped the sticky canvas right edge.
TempoTrackLane now renders like TimelineRuler — Fragment + spacer + canvas.

app/static/js/app.jsx

@@ -14985,10 +14985,7 @@ const App = () => {
       onRulerMouseDown: handleRulerMouseDown,
       scrollLeft: scrollLeft,
       canvasRedrawCount: canvasRedrawCount
-    }), /*#__PURE__*/React.createElement("div", {
-      className: "h-10 shrink-0 relative overflow-hidden",
-      style: { height: '40px' }
-    }, /*#__PURE__*/React.createElement(TempoTrackLane, {
+    }), /*#__PURE__*/React.createElement(TempoTrackLane, {
       bpm: parseInt(bpm) || 120,
       zoom: zoom,
       timelineWidth: timelineWidth,
@@ -14998,7 +14995,7 @@ const App = () => {
       onRulerMouseDown: handleRulerMouseDown,
       scrollLeft: scrollLeft,
       canvasRedrawCount: canvasRedrawCount
-    })), selectionMode === 'global' && selLeft !== null && selRight !== null && selRight > selLeft && /*#__PURE__*/React.createElement("div", {
+    }), selectionMode === 'global' && selLeft !== null && selRight !== null && selRight > selLeft && /*#__PURE__*/React.createElement("div", {
       className: "absolute inset-0 pointer-events-none z-20",
       style: {
         left: `${selLeft * zoom}px`,