training guide updates (#21674)

* add progress bar

* shorter

* update lane change speed

* fix

* center

* fix cutoff

selfdrive/ui/qt/offroad/onboarding.cc

@@ -34,12 +34,18 @@ void TrainingGuide::paintEvent(QPaintEvent *event) {
   QPainter painter(this);
 
   QRect bg(0, 0, painter.device()->width(), painter.device()->height());
-  QBrush bgBrush("#000000");
-  painter.fillRect(bg, bgBrush);
+  painter.fillRect(bg, QColor("#000000"));
 
   QRect rect(image.rect());
   rect.moveCenter(bg.center());
   painter.drawImage(rect.topLeft(), image);
+
+  // progress bar
+  if (currentIndex > 0 && currentIndex < (boundingRect.size() - 2)) {
+    const int h = 20;
+    const int w = (currentIndex / (float)(boundingRect.size() - 2)) * width();
+    painter.fillRect(QRect(0, height() - h, w, h), QColor("#465BEA"));
+  }
 }
 
 void TermsPage::showEvent(QShowEvent *event) {