feat: 三端抽屉重构 + 配色系统更新 + 后台管理页精调 + 键盘抬起组件

## 抽屉重构
- admin_drawer / doctor_drawer / health_drawer 三端抽屉全部重做
- drawer_shell 增强

## 配色系统
- app_colors / app_module_visuals / app_theme 更新
- app.dart 启动流程调整

## 后台管理页
- admin_doctors_page 大幅重构(+251)
- admin_home / doctor_dashboard / doctor_reports / doctor_home / doctor_followups / doctor_settings 精调

## 患者端
- home_page / chat_messages_view / medication_list / notification_center / remaining_pages / exercise_plan / device / diet / consultation 微调

## 新增
- keyboard_lift.dart: 键盘抬起处理组件
- AGENTS.md: agent 指引文档

## 其他
- api_client IP 适配
- app_future_view 增强
- data_providers 调整
- secondary_page_visuals_test 更新

health_app/test/secondary_page_visuals_test.dart

@@ -89,7 +89,9 @@ void main() {
         'lib/pages/auth/login_page.dart',
       ).readAsStringSync().replaceAll('\r\n', '\n');
 
-      expect(login, contains("Image.asset(\n              _loginBg"));
+      expect(login, contains("static const _loginBg = 'assets/"));
+      expect(login, contains('Image.asset('));
+      expect(login, contains('_loginBg,'));
       expect(login, contains('Colors.white.withValues(alpha: 0.88)'));
       expect(login, contains('fillColor: AppColors.cardInner'));
       expect(login, contains('showDragHandle: true'));
@@ -202,7 +204,10 @@ void main() {
         contains('foregroundColor: AppColors.textPrimary'),
       );
       expect(originalReportAction, contains('color: AppColors.border'));
-      expect(notifications, contains('BoxConstraints(minHeight: 82)'));
+      expect(
+        notifications,
+        contains('BoxConstraints(minHeight: showDivider ? 81 : 82)'),
+      );
       expect(notifications, contains('width: 68'));
       expect(notifications, contains("const TextSpan(text: ' 条未读消息')"));
       expect(