Add a Camera toggle to show the camera panel, hidden by default

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

myscan/app.py

@@ -475,7 +475,6 @@ class MainWindow(QMainWindow):
         if self.device is None:
             self.act_scan.setEnabled(False)
             self.act_scan.setToolTip("No myScan found (scanning needs Linux and the mouse plugged in)")
-            self.camera_pane.hide()
             self.set_message("No scanner found: open or drop an image to read it")
         else:
             self.start_scanner()
@@ -499,6 +498,9 @@ class MainWindow(QMainWindow):
             tb.addAction(a)
             return a
 
+        self.act_camera = act("Camera", lambda on: self.camera_pane.setVisible(on), "Ctrl+K",
+                              "Show the camera and the live sensor readings", True)
+        tb.addSeparator()
         self.act_scan = act("Start scan", self.toggle_scan, "F5", "Start or stop a scan (or press the mouse's scan button)")
         tb.addSeparator()
         act("Open…", self.open_image, QKeySequence.Open, "Open an image to read")
@@ -542,6 +544,7 @@ class MainWindow(QMainWindow):
         for w in (self.camera_pane, page_pane):
             main.addWidget(w)
         main.setSizes([220, 1180])
+        self.camera_pane.hide()
         self.setCentralWidget(main)
         self.status_label = QLabel()
         self.statusBar().addWidget(self.status_label, 1)