lock: aggressively reclaim keyboard focus on lock surface

modules/lock/LockSurface.qml

@@ -139,14 +139,26 @@ WlSessionLockSurface {
         }
     }
 
-    // Keyboard input - focus lives on an Item since WlSessionLockSurface is a window
+    // Keyboard input - focus lives on an Item since WlSessionLockSurface is a window.
+    // Aggressively reclaim focus: Component.onCompleted may fire before the surface
+    // is configured, and other items can steal activeFocus during layout.
     Item {
+        id: _keyInput
         anchors.fill: parent
         focus: true
         Keys.onPressed: event => {
             if (!root._unlocking)
                 root.auth.handleKey(event);
         }
+        onActiveFocusChanged: {
+            if (!activeFocus)
+                forceActiveFocus();
+        }
+    }
+
+    onVisibleChanged: {
+        if (visible)
+            _keyInput.forceActiveFocus();
     }
 
     // Unlock animation