feat: 更新应用名称和图标，优化用户界面

- 将应用名称修改为“Health Bot”，提升品牌识别度
- 更新应用图标为 logo.png，确保视觉一致性
- 删除不再使用的 ai-coach-chat 页面，简化代码结构
- 更新多个页面的导航和按钮文本，提升用户体验
- 添加体重历史记录功能，支持用户追踪健康数据
- 优化 Redux 状态管理，确保数据处理的准确性和稳定性

app.json

@@ -1,10 +1,10 @@
 {
   "expo": {
-    "name": "普拉提助手",
+    "name": "Health Bot",
     "slug": "digital-pilates",
     "version": "1.0.4",
     "orientation": "portrait",
-    "icon": "./assets/images/logo.jpeg",
+    "icon": "./assets/images/logo.png",
     "scheme": "digitalpilates",
     "userInterfaceStyle": "light",
     "newArchEnabled": true,
@@ -21,7 +21,7 @@
     },
     "android": {
       "adaptiveIcon": {
-        "foregroundImage": "./assets/images/logo.jpeg",
+        "foregroundImage": "./assets/images/logo.png",
         "backgroundColor": "#ffffff"
       },
       "edgeToEdgeEnabled": true,
@@ -30,14 +30,14 @@
     "web": {
       "bundler": "metro",
       "output": "static",
-      "favicon": "./assets/images/logo.jpeg"
+      "favicon": "./assets/images/logo.png"
     },
     "plugins": [
       "expo-router",
       [
         "expo-splash-screen",
         {
-          "image": "./assets/images/logo.jpeg",
+          "image": "./assets/images/logo.png",
           "imageWidth": 200,
           "resizeMode": "contain",
           "backgroundColor": "#ffffff"