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_edit_page.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import '../../core/app_colors.dart';
 import '../../core/app_theme.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../core/navigation_provider.dart';
@@ -57,7 +58,7 @@ class _MedicationEditPageState extends ConsumerState<MedicationEditPage> {
     try {
       if (widget.id != null) { await srv.update(widget.id!, data); } else { await srv.create(data); }
       ref.invalidate(medicationListProvider); ref.invalidate(medicationReminderProvider);
-      if (mounted) { ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('已保存'), backgroundColor: AppTheme.success)); popRoute(ref); }
+      if (mounted) { popRoute(ref); }
     } catch (_) { if (mounted) ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('保存失败'), backgroundColor: AppTheme.error)); }
     if (mounted) setState(() => _loading = false);
   }
@@ -113,24 +114,24 @@ class _MedicationEditPageState extends ConsumerState<MedicationEditPage> {
     );
   }
 
-  Widget _label(String text) => Text(text, style: const TextStyle(fontSize: 17, color: Color(0xFF666666)));
+  Widget _label(String text) => Text(text, style: TextStyle(fontSize: 17, color: AppColors.textSecondary));
   Widget _field(String label, TextEditingController ctrl, {String? hint}) => Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
     _label(label), const SizedBox(height: 6),
-    TextField(controller: ctrl, decoration: InputDecoration(hintText: hint, filled: true, fillColor: Colors.white, border: OutlineInputBorder(borderRadius: BorderRadius.circular(12), borderSide: BorderSide.none), contentPadding: const EdgeInsets.symmetric(horizontal: 12, vertical: 12)), style: const TextStyle(fontSize: 19)),
+    TextField(controller: ctrl, decoration: InputDecoration(hintText: hint, filled: true, fillColor: AppTheme.surface, border: OutlineInputBorder(borderRadius: BorderRadius.circular(AppTheme.rMd), borderSide: BorderSide.none), contentPadding: const EdgeInsets.symmetric(horizontal: 12, vertical: 12)), style: const TextStyle(fontSize: 19)),
   ]);
   Widget _chip(String label, bool sel, VoidCallback onTap) => GestureDetector(onTap: onTap, child: Container(padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8), decoration: BoxDecoration(color: sel ? AppTheme.primary : AppTheme.primaryLight, borderRadius: BorderRadius.circular(16)), child: Text(label, style: TextStyle(fontSize: 16, color: sel ? Colors.white : AppTheme.primary, fontWeight: FontWeight.w500))));
   Widget _dateField(String label, DateTime val, ValueChanged<DateTime> cb) => Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
     _label(label), const SizedBox(height: 6),
     GestureDetector(onTap: () async { final d = await showDatePicker(context: context, initialDate: val, firstDate: DateTime(2024), lastDate: DateTime(2030)); if (d != null) cb(d); },
-      child: Container(width: double.infinity, padding: const EdgeInsets.all(12), decoration: BoxDecoration(color: Colors.white, borderRadius: BorderRadius.circular(12)), child: Text('${val.month}/${val.day}', style: const TextStyle(fontSize: 18)))),
+      child: Container(width: double.infinity, padding: const EdgeInsets.all(12), decoration: BoxDecoration(color: AppTheme.surface, borderRadius: BorderRadius.circular(AppTheme.rMd)), child: Text('${val.month}/${val.day}', style: const TextStyle(fontSize: 18)))),
   ]);
   Widget _dateFieldOpt(String label, DateTime? val, ValueChanged<DateTime?> cb) => Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
     _label(label), const SizedBox(height: 6),
     GestureDetector(onTap: () async { final d = await showDatePicker(context: context, initialDate: val ?? DateTime.now(), firstDate: DateTime(2024), lastDate: DateTime(2030)); if (d != null) cb(d); },
-      child: Container(width: double.infinity, padding: const EdgeInsets.all(12), decoration: BoxDecoration(color: Colors.white, borderRadius: BorderRadius.circular(12)), child: Row(children: [
-        Text(val != null ? '${val.month}/${val.day}' : '不设置', style: TextStyle(fontSize: 18, color: val != null ? null : Colors.grey[400])),
+      child: Container(width: double.infinity, padding: const EdgeInsets.all(12), decoration: BoxDecoration(color: AppTheme.surface, borderRadius: BorderRadius.circular(AppTheme.rMd)), child: Row(children: [
+        Text(val != null ? '${val.month}/${val.day}' : '不设置', style: TextStyle(fontSize: 18, color: val != null ? null : AppTheme.textHint)),
         if (val != null) const Spacer(),
-        if (val != null) GestureDetector(onTap: () => cb(null), child: const Icon(Icons.close, size: 19, color: Color(0xFFBBBBBB))),
+        if (val != null) GestureDetector(onTap: () => cb(null), child: const Icon(Icons.close, size: 19, color: AppColors.textHint)),
       ]))),
   ]);
 }