feat: AI 对话附件上下文解析 + 历史会话归档 + 多页面 UI 重构

- 后端: 新增 AttachmentContextBuilder 解析图片/PDF 摘要并拼入 LLM 上下文; ai_chat_endpoints 扩展附件接口; 新增 ReportAnalysisService
- 前端: 新增历史会话页与 conversation_history_provider; chat 链路支持附件展示与回放
- UI: 重构 medication_checkin / notification_center / profile / health_drawer 等多页面
- 配置: api_client baseUrl 适配当前 WiFi IP

health_app/lib/core/navigation_provider.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/widgets.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 /// 路由信息
@@ -39,17 +40,25 @@ final currentRouteProvider = Provider<RouteInfo>((ref) {
   return stack.last;
 });
 
+/// 路由切换前清理键盘焦点，避免返回页面时键盘自动弹起
+void _dismissKeyboard() {
+  FocusManager.instance.primaryFocus?.unfocus();
+}
+
 /// 跳转（替换整个栈）
 void goRoute(WidgetRef ref, String name, {Map<String, String> params = const {}}) {
+  _dismissKeyboard();
   ref.read(routeStackProvider.notifier).replace(name, params: params);
 }
 
 /// 推入新页面
 void pushRoute(WidgetRef ref, String name, {Map<String, String> params = const {}}) {
+  _dismissKeyboard();
   ref.read(routeStackProvider.notifier).push(name, params: params);
 }
 
 /// 返回上一页
 void popRoute(WidgetRef ref) {
+  _dismissKeyboard();
   ref.read(routeStackProvider.notifier).pop();
 }