refactor(gui): 更新加载界面资源及配置

- 删除未使用的背景资源mp2.png及其相关文件
- 更新umps.plist和umps.png资源文件
- 调整loading.prefab的激活状态和位置
- 优化资源引用和配置

assets/resources/gui/umps.plist.meta

@@ -7,6 +7,52 @@
     ".json"
   ],
   "subMetas": {
+    "8b868": {
+      "importer": "sprite-frame",
+      "uuid": "d7d869bc-06aa-4876-806f-487e68b96780@8b868",
+      "displayName": "",
+      "id": "8b868",
+      "name": "Background_01",
+      "userData": {
+        "trimThreshold": 1,
+        "rotated": false,
+        "offsetX": 0,
+        "offsetY": 0,
+        "trimX": 651,
+        "trimY": 1,
+        "width": 324,
+        "height": 666,
+        "rawWidth": 324,
+        "rawHeight": 666,
+        "borderTop": 0,
+        "borderBottom": 0,
+        "borderLeft": 0,
+        "borderRight": 0,
+        "packable": true,
+        "pixelsToUnit": 100,
+        "pivotX": 0.5,
+        "pivotY": 0.5,
+        "meshType": 0,
+        "vertices": {
+          "rawPosition": [],
+          "indexes": [],
+          "uv": [],
+          "nuv": [],
+          "minPos": [],
+          "maxPos": []
+        },
+        "isUuid": true,
+        "imageUuidOrDatabaseUri": "cd375c0d-bb84-48dc-a7ec-334d7ce1471b@6c48a",
+        "atlasUuid": "d7d869bc-06aa-4876-806f-487e68b96780",
+        "trimType": "auto"
+      },
+      "ver": "1.0.12",
+      "imported": true,
+      "files": [
+        ".json"
+      ],
+      "subMetas": {}
+    },
     "54dda": {
       "importer": "sprite-frame",
       "uuid": "d7d869bc-06aa-4876-806f-487e68b96780@54dda",