latch lock screen animations after first wave completes

shell/lock/LockSurface.qml

@@ -28,13 +28,23 @@ WlSessionLockSurface {
         anchors.fill: parent
         opacity: _unlockFade
 
-        layer.enabled: true
+        property bool _revealed: false
+
+        layer.enabled: !_revealed
         layer.effect: ShaderEffect {
             property real uPhase: _hexWave.wavePhase
             property real uWidth: root.width
             fragmentShader: Quickshell.shellPath("modules/reveal_mask.frag.qsb")
         }
 
+        Connections {
+            target: _hexWave
+            function onWavePhaseChanged() {
+                if (!parent._revealed && _hexWave.wavePhase >= root.width)
+                    parent._revealed = true;
+            }
+        }
+
         // Blurred screenshot
         ScreencopyView {
             anchors.fill: parent