Fix erratic axis scaling when hovering over plots

InfiniteLine was included in auto-range calculations, causing the view
to rescale on every cursor move. Add it with ignoreBounds=True in both
the initial setup and after each redraw.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gui_client.py

@@ -363,7 +363,7 @@ class PlotTab(QWidget):
                 pen=pg.mkPen("gray", width=1, style=Qt.DashLine),
             )
             vl.setVisible(False)
-            pw.addItem(vl)
+            pw.addItem(vl, ignoreBounds=True)
             self._vlines.append(vl)
 
             proxy = pg.SignalProxy(
@@ -504,7 +504,7 @@ class PlotTab(QWidget):
         for i, pw in enumerate(self._plot_widgets):
             pi = pw.getPlotItem()
             pi.clear()
-            pi.addItem(self._vlines[i])
+            pi.addItem(self._vlines[i], ignoreBounds=True)
             if pi.legend:
                 pi.legend.clear()