feat: enable back to original size after exit fullscreen.

After exit fullscreen, it still show as fullscreen with title, this make user feel unwell. Record the normal size and then recover will be beter.

Log: support recover size.

QtScrcpy/ui/videoform.cpp

@@ -467,6 +467,8 @@ void VideoForm::switchFullScreen()
         }
 
         showNormal();
+        // back to normal size.
+        resize(m_normalSize);
         // fullscreen window will move (0,0). qt bug?
         move(m_fullScreenBeforePos);
 
@@ -487,6 +489,9 @@ void VideoForm::switchFullScreen()
             ui->keepRatioWidget->setWidthHeightRatio(-1.0f);
         }
 
+        // record current size before fullscreen, it will be used to rollback size after exit fullscreen.
+        m_normalSize = size();
+
         m_fullScreenBeforePos = pos();
         // 这种临时增加标题栏再全屏的方案会导致收不到mousemove事件，导致setmousetrack失效
         // mac fullscreen must show title bar

QtScrcpy/ui/videoform.h

@@ -79,6 +79,7 @@ private:
 
     //inside member
     QSize m_frameSize;
+    QSize m_normalSize;
     QPoint m_dragPosition;
     float m_widthHeightRatio = 0.5f;
     bool m_skin = true;