fix: 修复 Flutter 前端多项功能 + 后端运动计划 API

- Android 添加相机/存储权限，拍照和相册功能可用
- AI 回复支持 Markdown 渲染（加粗/表格不再显示**乱码）
- 附件按钮接线，支持拍照/相册/文件选择
- 智能体面板按钮全部接线（拍照/上传/手动录入/导航）
- 侧边栏 AI 录入后自动刷新健康数据
- 运动计划页增加创建按钮 + 打卡功能
- 后端运动计划支持 AI 创建和打卡（Tool Calling）
- 修复 CreateExercisePlanRequest JSON 反序列化

health_app/pubspec.lock

@@ -230,6 +230,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_markdown:
+    dependency: "direct main"
+    description:
+      name: flutter_markdown
+      sha256: "08fb8315236099ff8e90cb87bb2b935e0a724a3af1623000a9cec930468e0f27"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.7+1"
   flutter_plugin_android_lifecycle:
     dependency: transitive
     description:
@@ -416,6 +424,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.3.0"
+  markdown:
+    dependency: transitive
+    description:
+      name: markdown
+      sha256: ee85086ad7698b42522c6ad42fe195f1b9898e4d974a1af4576c1a3a176cada9
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.3.1"
   matcher:
     dependency: transitive
     description: