feat: 医生端完整实现 + 双角色登录 + 健康日历 + 饮食记录重做 + 配色系统重构

后端:
- User表加Role字段 + DoctorProfile表 + 废弃旧Doctor数据
- JWT加Role claim + 注册/登录拆分(/api/auth/register + /api/auth/login)
- 医生端点全量加JWT鉴权+Role校验(15个端点)
- 日历端点改造(用药/运动/随访按日期+星期匹配)
- 饮食记录PUT端点 + 健康记录DELETE端点
- 用户Profile端点返回Role

前端:
- 登录页重做(角色选择卡片 用户紫/医生蓝 + 审核码6666 + 注册返登录)
- App路由分流(userRole→患者端/医生端)
- 医生端: 工作台Dashboard + 患者管理(搜索分页) + 问诊/报告/随访CRUD
- 报告审核: AI预分析+指标表格+严重程度4级+模板多选+评语
- 随访编辑: 患者选择器+日期时间+打通患者端
- 健康日历: 可点击日历+当日安排列表+用药/运动/随访颜色标记
- 饮食记录: 热量趋势7/30天+日历(一周)+当日胶囊详情+侧滑编辑删除
- 健康档案: 日期选择器+手术可添加多条+白底渐变保存按钮
- 配色系统: 清理25个未使用色+新增doctorBlue/drawerGradient/pageGrey
- 患者端侧边栏: 新渐变+白底按钮+紫色汉堡图标
- AI对话: 用户气泡白底黑字+药管家改蓝色
- App启动闪屏: 防登录页闪烁

文档: color_design_system.md(20页面完整配色设计+图标底色对照表)

health_app/lib/pages/home/widgets/chat_messages_view.dart

@@ -904,14 +904,14 @@ class ChatMessagesView extends ConsumerWidget {
         constraints: BoxConstraints(maxWidth: MediaQuery.of(context).size.width * 0.82),
         padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
         decoration: BoxDecoration(
-          color: isUser ? AppTheme.primary : AppColors.cardBackground,
+          color: isUser ? Colors.white : AppColors.cardBackground,
           borderRadius: BorderRadius.only(
             topLeft: Radius.circular(isUser ? 20 : 4),
             topRight: Radius.circular(isUser ? 4 : 20),
             bottomLeft: const Radius.circular(20),
             bottomRight: const Radius.circular(20),
           ),
-          border: isUser ? null : Border.all(color: AppColors.border, width: 1.5),
+          border: Border.all(color: isUser ? const Color(0xFFE8E4FF) : AppColors.border, width: isUser ? 1 : 1.5),
           boxShadow: isUser ? [] : [BoxShadow(color: AppTheme.primary.withAlpha(12), blurRadius: 10, offset: const Offset(0, 3))],
         ),
         child: Column(
@@ -919,7 +919,7 @@ class ChatMessagesView extends ConsumerWidget {
             children: [
               // 文字内容
               if (isUser)
-                SelectableText(msg.content, style: const TextStyle(fontSize: 19, color: Colors.white, height: 1.5))
+                SelectableText(msg.content, style: const TextStyle(fontSize: 19, color: AppColors.textPrimary, height: 1.5))
               else
                 MarkdownBody(
                   data: _cleanAiText(msg.content),
@@ -1160,11 +1160,11 @@ class ChatMessagesView extends ConsumerWidget {
         accent: const Color(0xFFF0A060),
       ),
       ActiveAgent.medication => _AgentColors(
-        gradient: [const Color(0xFFB8E0D8), const Color(0xFF8ED4C8), const Color(0xFF68B8AC)],
-        bg: const Color(0xFFF0FAF8),
-        border: const Color(0xFFD4ECE8),
-        iconBg: const Color(0xFFE4F6F2),
-        accent: const Color(0xFF68B8AC),
+        gradient: [const Color(0xFFB0CCF8), const Color(0xFF7DA8F0), const Color(0xFF4A80E8)],
+        bg: const Color(0xFFEEF2FF),
+        border: const Color(0xFFC8D8FA),
+        iconBg: const Color(0xFFDEE6FC),
+        accent: const Color(0xFF4A80E8),
       ),
       ActiveAgent.report => _AgentColors(
         gradient: [const Color(0xFFD8D0F0), const Color(0xFFC4B8EC), const Color(0xFFA898D8)],
@@ -1359,7 +1359,7 @@ class ChatMessagesView extends ConsumerWidget {
       child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
         Container(
           width: double.infinity, padding: const EdgeInsets.fromLTRB(16, 12, 16, 10),
-          decoration: const BoxDecoration(gradient: LinearGradient(colors: [Color(0xFFF0ECFF), Color(0xFFEBF4FF)])),
+          decoration: const BoxDecoration(gradient: AppColors.drawerGradient),
           child: Row(children: [
             Container(width: 28, height: 28, decoration: BoxDecoration(color: Colors.white.withOpacity(0.6), borderRadius: BorderRadius.circular(8)),
               child: const Icon(Icons.health_and_safety, size: 16, color: AppColors.primary)),