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/widgets/common_widgets.dart

@@ -23,7 +23,7 @@ class GradientBorderButton extends StatelessWidget {
     return Container(
       height: height,
       decoration: BoxDecoration(
-        gradient: isSuccess ? AppColors.successButtonGradient : AppColors.buttonGradient,
+        gradient: isSuccess ? AppColors.primaryGradient : AppColors.primaryGradient,
         borderRadius: BorderRadius.circular(14),
         boxShadow: AppColors.buttonShadow,
       ),
@@ -78,14 +78,14 @@ class CardActionButton extends StatelessWidget {
       child: Container(
         padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
         decoration: BoxDecoration(
-          color: AppColors.backgroundSecondary,
+          color: AppColors.cardInner,
           borderRadius: BorderRadius.circular(12),
           border: Border.all(color: AppColors.borderLight),
         ),
         child: Row(
           mainAxisSize: MainAxisSize.min,
           children: [
-            Icon(icon, size: 18, color: iconColor ?? AppColors.iconColor),
+            Icon(icon, size: 18, color: iconColor ?? AppColors.primary),
             const SizedBox(width: 6),
             Text(
               label,
@@ -102,6 +102,63 @@ class CardActionButton extends StatelessWidget {
   }
 }
 
+/// 滑动删除组件：左滑露出红色删除背景，达30%阈值锁定，点击确认删除
+/// [margin] 控制卡片之间的间距，red背景与child完全对齐
+class SwipeDeleteTile extends StatefulWidget {
+  final Widget child;
+  final VoidCallback onDelete;
+  final VoidCallback? onTap;
+  final EdgeInsetsGeometry margin;
+  const SwipeDeleteTile({super.key, required this.child, required this.onDelete, this.onTap, this.margin = const EdgeInsets.symmetric(horizontal: 16, vertical: 4)});
+  @override State<SwipeDeleteTile> createState() => _SwipeDeleteTileState();
+}
+
+class _SwipeDeleteTileState extends State<SwipeDeleteTile> with SingleTickerProviderStateMixin {
+  double _dx = 0;
+  static const _maxSlide = 80.0;
+  static const _threshold = 24.0; // 30% of 80
+
+  void _onDragUpdate(DragUpdateDetails d) {
+    setState(() => _dx = (_dx + d.delta.dx).clamp(-_maxSlide, 0.0));
+  }
+
+  void _onDragEnd(DragEndDetails d) {
+    if (_dx < -_threshold) {
+      setState(() => _dx = -_maxSlide);
+    } else {
+      setState(() => _dx = 0);
+    }
+  }
+
+  @override Widget build(BuildContext context) {
+    final isSwiped = _dx < 0;
+    return Padding(
+      padding: widget.margin,
+      child: Stack(children: [
+        Positioned.fill(child: Container(
+          decoration: BoxDecoration(color: AppColors.error, borderRadius: BorderRadius.circular(16)),
+          child: const Align(
+            alignment: Alignment.centerRight,
+            child: Padding(padding: EdgeInsets.only(right: 20), child: Icon(Icons.delete_outline, color: AppColors.textOnGradient, size: 28)),
+          ),
+        )),
+        GestureDetector(
+          behavior: isSwiped ? HitTestBehavior.opaque : HitTestBehavior.deferToChild,
+          onTap: isSwiped ? () { widget.onDelete(); setState(() => _dx = 0); } : widget.onTap,
+          onHorizontalDragUpdate: _onDragUpdate,
+          onHorizontalDragEnd: _onDragEnd,
+          child: Transform.translate(
+            offset: Offset(_dx, 0),
+            child: isSwiped
+                ? AbsorbPointer(absorbing: true, child: widget.child)
+                : widget.child,
+          ),
+        ),
+      ]),
+    );
+  }
+}
+
 /// 功能区小图标容器
 class IconBox extends StatelessWidget {
   final IconData icon;
@@ -123,13 +180,13 @@ class IconBox extends StatelessWidget {
       width: size,
       height: size,
       decoration: BoxDecoration(
-        color: backgroundColor ?? AppColors.iconBackground,
+        color: backgroundColor ?? AppColors.iconBg,
         borderRadius: BorderRadius.circular(size / 3),
       ),
       child: Icon(
         icon,
         size: size * 0.55,
-        color: iconColor ?? AppColors.iconColor,
+        color: iconColor ?? AppColors.primary,
       ),
     );
   }