fix: black screen resume / pause (#2400)

client/ui/qml/main2.qml

@@ -23,17 +23,25 @@ Window  {
                 if (Qt.application.state === Qt.ApplicationActive) {
                     root.visible = true
                     refreshTimer.restart()
-                } else if (Qt.application.state === Qt.ApplicationSuspended) {
-                    // Hide window to stop the Qt render loop and prevent
-                    // eglSwapBuffers from being called on a lost EGL context.
-                    // NOTE: Do NOT hide on ApplicationInactive — that fires on any
-                    // focus change (IME, notifications) and would blank the screen.
-                    root.visible = false
                 }
             }
         }
     }
 
+    // Hide the window immediately when Android Activity.onPause() fires so that
+    // Qt's render loop stops before the EGL surface is disconnected.  This
+    // prevents "QRhiGles2: Failed to make context current" and the resulting
+    // black screen that appears after swiping home and returning.
+    Connections {
+        target: SettingsController
+        function onActivityPaused() {
+            if (Qt.platform.os === "android") root.visible = false
+        }
+        function onActivityResumed() {
+            if (Qt.platform.os === "android") root.visible = true
+        }
+    }
+
     Timer {
         id: refreshTimer
         interval: 150