refactor(hero&mission): 调整英雄站位逻辑与配置

1.  修改游戏地平线Y轴偏移至100，适配新的UI布局
2.  为英雄属性组件添加分路与排位字段并初始化
3.  重构英雄站位分配逻辑，使用新增字段记录英雄位置
4.  更新地图与UI预制体的布局偏移适配新的游戏地平线

assets/resources/gui/element/mission.prefab

@@ -1201,7 +1201,7 @@
     "_lpos": {
       "__type__": "cc.Vec3",
       "x": 0,
-      "y": 309.135,
+      "y": 242.874,
       "z": 0
     },
     "_lrot": {
@@ -1254,7 +1254,7 @@
     "_lpos": {
       "__type__": "cc.Vec3",
       "x": -350,
-      "y": 93.364,
+      "y": 221.748,
       "z": 0
     },
     "_lrot": {
@@ -1324,8 +1324,8 @@
     "_target": null,
     "_left": 10,
     "_right": 10,
-    "_top": 21.635999999999996,
-    "_bottom": 8.364000000000004,
+    "_top": -106.74799999999999,
+    "_bottom": 136.748,
     "_horizontalCenter": 0,
     "_verticalCenter": 0,
     "_isAbsLeft": true,
@@ -1357,7 +1357,7 @@
       "__id__": 53
     },
     "_resizeMode": 0,
-    "_layoutType": 1,
+    "_layoutType": 3,
     "_cellSize": {
       "__type__": "cc.Size",
       "width": 40,
@@ -1369,10 +1369,10 @@
     "_paddingTop": 0,
     "_paddingBottom": 0,
     "_spacingX": 5,
-    "_spacingY": 0,
+    "_spacingY": 20,
     "_verticalDirection": 1,
     "_horizontalDirection": 0,
-    "_constraint": 0,
+    "_constraint": 1,
     "_constraintNum": 2,
     "_affectedByScale": false,
     "_isAlign": true,
@@ -2126,7 +2126,7 @@
     "_left": 0,
     "_right": 0,
     "_top": 0,
-    "_bottom": 309.135,
+    "_bottom": 242.874,
     "_horizontalCenter": 0,
     "_verticalCenter": 0,
     "_isAbsLeft": true,