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/win32_utils.py

@@ -80,5 +80,10 @@ else:
         _user32.ShowWindow(hwnd, _SW_MAXIMIZE)
         _user32.SetForegroundWindow(hwnd)
 
+    def minimize_window(hwnd: int) -> None:
+        """Minimize a window to taskbar to free GPU resources."""
+        _SW_MINIMIZE = 6
+        _user32.ShowWindow(hwnd, _SW_MINIMIZE)
+
     def is_window_alive(hwnd: int) -> bool:
         return bool(_user32.IsWindow(hwnd))