新增宣传页 Mock 模块并接入首页路由。

从 xh_test 同步 ScenicPromotion 演示页，补齐 MVVM 结构、本地资源、单元测试与模块文档，注册 promotion_page 首页入口。

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan/Assets.xcassets/ScenicPromotionThumbGrass.imageset/Contents.json

@@ -0,0 +1,21 @@
+{
+  "images" : [
+    {
+      "filename" : "scenic_promotion_thumb_grass.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}