feat: rework wallpaper to use stack instead of A/B

Also switch colour animation to SlowEffects

components/CAnim.qml

@@ -2,6 +2,6 @@ import QtQuick
 import Caelestia.Config
 
 ColorAnimation {
-    duration: Tokens.anim.durations.normal
+    duration: Tokens.anim.durations.expressiveSlowEffects
-    easing: Tokens.anim.standard
+    easing: Tokens.anim.expressiveSlowEffects
 }

modules/background/Wallpaper.qml

@@ -12,22 +12,24 @@ Item {
     id: root
 
     property string source: Wallpapers.current
-    property Image current: one
+    property CachingImage current
     property bool completed
 
     onSourceChanged: {
         if (!source)
             current = null;
-        else if (current === one)
-            two.update();
         else
-            one.update();
+            current = imgComp.createObject(this, {
+                path: source
+            });
     }
 
     Component.onCompleted: {
         if (source)
             Qt.callLater(() => {
-                one.update();
+                current = imgComp.createObject(this, {
+                    path: source
+                });
                 completed = true;
             });
     }
@@ -98,48 +100,34 @@ Item {
         }
     }
 
-    Img {
+    Component {
-        id: one
+        id: imgComp
-    }
 
-    Img {
+        CachingImage {
-        id: two
-    }
-
-    component Img: CachingImage {
             id: img
 
-        function update(): void {
-            if (path === root.source)
-                root.current = this;
-            else
-                path = root.source;
-        }
-
             anchors.fill: parent
 
             opacity: 0
-        scale: Wallpapers.showPreview ? 1 : 0.8
 
             onStatusChanged: {
                 if (status === Image.Ready)
-                root.current = this;
+                    anim.start();
             }
 
-        states: State {
+            Anim on opacity {
-            name: "visible"
+                id: anim
-            when: root.current === img
 
-            PropertyChanges {
+                type: Anim.SlowEffects
-                img.opacity: 1
+                running: false
-                img.scale: 1
+                from: 0
-            }
+                to: 1
             }
 
-        transitions: Transition {
+            Timer {
-            Anim {
+                running: root.current !== img && root.current?.status === Image.Ready
-                target: img
+                interval: anim.duration
-                properties: "opacity,scale"
+                onTriggered: img.destroy()
             }
         }
     }