feat(mission): 更新关卡显示与回合提示逻辑

1. 调整关卡UI文本格式，添加回合数显示并缩小字体
2. 新增监听回合进度数据源，更新注释描述
3. 重构阶段过滤逻辑，补充PrepareStart/End阶段的排除
4. 将回合开始提示移至BattleStart阶段播放，优化提示显示时机
5. 修正回合管理相关注释与逻辑，移除旧的首回合延迟提示

assets/resources/gui/element/mission.prefab

@@ -5746,10 +5746,10 @@
       "b": 255,
       "a": 255
     },
-    "_string": "第 {{0}}-{{1}}关",
+    "_string": "第 {{0}} - {{1}}关  {{2}}回合",
     "_horizontalAlign": 1,
     "_verticalAlign": 1,
-    "_actualFontSize": 26,
+    "_actualFontSize": 17,
     "_fontSize": 25,
     "_fontFamily": "Arial",
     "_lineHeight": 40,
@@ -5809,7 +5809,8 @@
     "labelType": "cc.Label",
     "watchPathArr": [
       "data.stage_progress.chapter ",
-      "data.stage_progress.stage"
+      "data.stage_progress.stage",
+      "data.stage_progress.section"
     ],
     "_id": ""
   },