feat: UI全面改造 + 后端多项修复

【后端修复】
- 删除diet/consultation agent假工具声明
- 修复DayOfWeek实体注释
- 修复Vision API content序列化
- cleanup_service级联删除修复
- 用药提醒时区偏差修复
- 统一DateTime处理(UtcNow+8)
- 新增UTC DateTime JSON转换器

【前端UI重构】
- 配色体系全面更新(#8B5CF6淡紫+#F0ECFF背景)
- 登录页重设计
- 首页重设计(透明顶栏、渐变背景、胶囊输入区)
- 聊天卡片加白蓝边框、渐变标题
- 侧边栏重构(渐变背景、合并顶部、删除底部设置)
- 确认卡片可编辑字段恢复
- 所有子页面加返回按钮
- catch异常加日志
- 删除后refresh provider缓存

health_app/lib/pages/medication/medication_checkin_page.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
+import '../../core/app_colors.dart';
 import '../../core/app_theme.dart';
+import '../../core/navigation_provider.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../providers/auth_provider.dart';
 import '../../providers/data_providers.dart';
@@ -29,13 +31,13 @@ class _MedicationCheckInPageState extends ConsumerState<MedicationCheckInPage> {
       ref.invalidate(medicationReminderProvider);
       ref.invalidate(medicationListProvider);
       _load();
-    } catch (_) {}
+    } catch (e) { debugPrint('[MedCheckIn] 打卡失败: $e'); }
   }
 
   @override Widget build(BuildContext context) {
     return Scaffold(
       backgroundColor: AppTheme.bg,
-      appBar: AppBar(title: const Text('服药打卡'), centerTitle: true),
+      appBar: AppBar(leading: IconButton(icon: const Icon(Icons.arrow_back), onPressed: () => popRoute(ref)), title: const Text('服药打卡'), centerTitle: true),
       body: FutureBuilder<List<Map<String, dynamic>>>(
         future: _future,
         builder: (ctx, snap) {
@@ -46,9 +48,9 @@ class _MedicationCheckInPageState extends ConsumerState<MedicationCheckInPage> {
           if (reminders.isEmpty) {
             return Center(
               child: Column(mainAxisSize: MainAxisSize.min, children: [
-                Icon(Icons.check_circle_outline, size: 64, color: Colors.grey[300]),
+                Icon(Icons.check_circle_outline, size: 64, color: AppTheme.textHint),
                 const SizedBox(height: 12),
-                const Text('今天所有用药已打卡', style: TextStyle(fontSize: 19, color: Color(0xFF999999))),
+                const Text('今天所有用药已打卡', style: TextStyle(fontSize: 19, color: AppColors.textSecondary)),
               ]),
             );
           }
@@ -78,21 +80,21 @@ class _MedicationCheckInPageState extends ConsumerState<MedicationCheckInPage> {
                   margin: const EdgeInsets.only(bottom: 12),
                   padding: const EdgeInsets.all(16),
                   decoration: BoxDecoration(
-                    color: Colors.white,
-                    borderRadius: BorderRadius.circular(16),
-                    boxShadow: [BoxShadow(color: AppTheme.primary.withAlpha(10), blurRadius: 8, offset: const Offset(0, 2))],
+                    color: AppTheme.surface,
+                    borderRadius: BorderRadius.circular(AppTheme.rLg),
+                    boxShadow: [AppTheme.shadowCard],
                   ),
                   child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
                     Row(children: [
                       Container(
                         width: 40, height: 40,
-                        decoration: BoxDecoration(color: const Color(0xFFFFF3E0), borderRadius: BorderRadius.circular(10)),
+                        decoration: BoxDecoration(color: AppColors.warningLight, borderRadius: BorderRadius.circular(10)),
                         child: const Center(child: Text('💊', style: TextStyle(fontSize: 23))),
                       ),
                       const SizedBox(width: 12),
                       Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
                         Text(medName, style: const TextStyle(fontSize: 19, fontWeight: FontWeight.w700)),
-                        if (dosage.isNotEmpty) Text(dosage, style: const TextStyle(fontSize: 16, color: Color(0xFF888888))),
+                        if (dosage.isNotEmpty) Text(dosage, style: const TextStyle(fontSize: 16, color: AppColors.textSecondary)),
                       ]),
                     ]),
                     const SizedBox(height: 14),
@@ -107,12 +109,12 @@ class _MedicationCheckInPageState extends ConsumerState<MedicationCheckInPage> {
                           Icon(
                             isTaken ? Icons.check_circle : Icons.radio_button_unchecked,
                             size: 23,
-                            color: isTaken ? AppTheme.success : const Color(0xFFCCCCCC),
+                            color: isTaken ? AppTheme.success : AppTheme.border,
                           ),
                           const SizedBox(width: 10),
                           Text(time, style: TextStyle(
                             fontSize: 18, fontWeight: FontWeight.w500,
-                            color: isTaken ? const Color(0xFF999999) : const Color(0xFF333333),
+                            color: isTaken ? AppTheme.textSub : AppTheme.text,
                           )),
                           const Spacer(),
                           GestureDetector(
@@ -120,12 +122,12 @@ class _MedicationCheckInPageState extends ConsumerState<MedicationCheckInPage> {
                             child: Container(
                               padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                               decoration: BoxDecoration(
-                                color: isTaken ? const Color(0xFFDCFCE7) : AppTheme.primary,
+                                color: isTaken ? AppColors.successLight : AppTheme.primary,
                                 borderRadius: BorderRadius.circular(20),
                               ),
                               child: Text(isTaken ? '已打卡' : '打卡',
                                 style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600,
-                                  color: isTaken ? AppTheme.success : Colors.white)),
+                                  color: isTaken ? AppTheme.success : AppColors.textOnGradient)),
                             ),
                           ),
                         ]),