feat: cruise warning signs and speed limit sign sizing

Cruise warning sign appears above speed limit sign when cruise set
speed is too far from the speed limit:
- Red (over): cruise >= limit + 10 (if limit >= 50) or + 5 (if < 50)
- Green (under): cruise <= limit - 5
- Only when cruise active (not paused/disabled) and limit >= 20
- Nightrider mode: colored text/border on black background

Speed limit sign enlarged 5%. 20px gap between signs. Bench mode
gains cruiseactive command (0=disabled, 1=active, 2=paused).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/ui/qt/onroad.h

@@ -52,6 +52,7 @@ private:
   void drawText(QPainter &p, int x, int y, const QString &text, int alpha = 255);
   void drawSpeedWidget(QPainter &p, int x, int y, const QString &title, const QString &speedLimitStr, QColor colorSpeed, int width = 176);
   void drawSpeedLimitSign(QPainter &p);
+  void drawCruiseWarningSign(QPainter &p);
 
   QVBoxLayout *main_layout;
   QPixmap dm_img;
@@ -66,6 +67,8 @@ private:
   QString clpSpeedDisplay;
   QString clpSpeedLimitDisplay;
   QString clpSpeedUnit;
+  QString clpCruiseWarning;
+  QString clpCruiseWarningSpeed;
   int clpParamFrame = 0;
 
   float setSpeed;