feat: 饮食记录逻辑重构 + 通知管理分隔线修复 + 多页面 UI 调整

- 饮食: 新增 DietCommentaryPolicy + diet_record_logic, 饮食记录逻辑抽取复用
- 通知管理: 分隔线改为仿通知中心样式, 跳过图标区域只留文字下方
- 侧边栏: 对话记录操作栏浮层修复 + 常用功能间距收紧
- 智能体: 欢迎卡片去 400ms 延迟 + 胶囊去阴影
- 后端: AI 会话仓库新增方法 + 饮食评论策略 + 健康记录规则调整
- 其他: api_client IP 适配 + 多页面 UI 微调 + 新增测试

health_app/lib/pages/device/device_management_page.dart

@@ -685,12 +685,12 @@ class _EmptyDevices extends StatelessWidget {
             width: 72,
             height: 72,
             decoration: BoxDecoration(
-              color: const Color(0xFFEFF6FF),
+              color: AppColors.deviceLight,
               borderRadius: BorderRadius.circular(22),
             ),
             child: const Icon(
               Icons.bluetooth_disabled_rounded,
-              color: Color(0xFF2563EB),
+              color: AppColors.device,
               size: 36,
             ),
           ),
@@ -747,7 +747,7 @@ class _ScanIndicator extends StatelessWidget {
                 height: 78 * animation.value,
                 decoration: BoxDecoration(
                   shape: BoxShape.circle,
-                  color: const Color(0xFF2563EB).withValues(alpha: 0.10),
+                  color: AppColors.device.withValues(alpha: 0.10),
                 ),
               ),
             ),
@@ -758,7 +758,7 @@ class _ScanIndicator extends StatelessWidget {
                 height: 64 * animation.value,
                 decoration: BoxDecoration(
                   shape: BoxShape.circle,
-                  color: const Color(0xFF2563EB).withValues(alpha: 0.18),
+                  color: AppColors.device.withValues(alpha: 0.18),
                 ),
               ),
             ),
@@ -767,11 +767,11 @@ class _ScanIndicator extends StatelessWidget {
             width: 58,
             height: 58,
             decoration: BoxDecoration(
-              color: const Color(0xFF2563EB),
+              color: AppColors.device,
               shape: BoxShape.circle,
               boxShadow: [
                 BoxShadow(
-                  color: const Color(0xFF2563EB).withValues(alpha: 0.24),
+                  color: AppColors.device.withValues(alpha: 0.24),
                   blurRadius: 18,
                   offset: const Offset(0, 8),
                 ),