fix(display-manager): lazy launch by default + minimize unassigned apps

- autolaunch default: True → False (on-demand only, saves GPU on startup)
- add ProcessManager.minimize() to minimize a window to taskbar
- add win32_utils.minimize_window() (SW_MINIMIZE via user32)
- DisplayManager._minimize_unassigned(): after each app switch, minimize
  every running app not currently assigned to any screen, freeing iGPU
  resources (critical on J6412 UHD 600 with limited EUs)

Background: J6412 Intel UHD 600 has only 16 EUs @ 800 MHz. Running
AR-ECDIS (MapLibre GL) and GPS (OpenLayers) simultaneously consumes ~60%
iGPU. By minimizing inactive apps Windows suspends their GPU presentation
chain, dropping idle GPU load near zero.

AR_electronics — AR-Autopilot Project

display_manager/display_manager.py

@@ -106,6 +106,18 @@ class DisplayManager(QObject):
             self._bring_app(app_id, screen_geo)
 
         self._layout.set(screen_serial, app_id)
+        # Minimize apps not assigned to any screen (free GPU)
+        self._minimize_unassigned()
+
+    def _minimize_unassigned(self) -> None:
+        """Minimize every running app that is not currently assigned to any screen."""
+        assigned = set(
+            self._layout.get(self._screen_serial(s))
+            for s in self._app.screens()
+        ) - {None}
+        for app_id in self._proc_mgr.running_ids():
+            if app_id not in assigned:
+                self._proc_mgr.minimize(app_id)
 
     def _bring_app(self, app_id: str, geo: QRect) -> None:
         self._proc_mgr.bring_to_screen(app_id, geo.x(), geo.y(), geo.width(), geo.height())