feat(wish-tree): 许愿树游戏化改造

- 前端：全屏Canvas场景，夜空/云朵/草地/大树
- 前端：丝带系统，支持陀螺仪和麦克风交互
- 前端：弹幕许愿展示
- 前端：多棵树切换（祈福树/姻缘树/事业树）
- 后端：新增GET /api/wish/trees获取树列表
- 后端：新增GET /api/wish/tree/:id/wishes获取树许愿
- 后端：WishTree模型新增Type、Sort字段
- 后端：AutoMigrate自动处理表结构变更
- 后端：seedDefaultData自动初始化默认数据
- 数据库：wish_trees表新增type、sort字段

server/internal/service/wish.go

@@ -23,6 +23,15 @@ func NewWishService() *WishService {
 	}
 }
 
+// GetWishTrees 获取许愿树列表
+func (s *WishService) GetWishTrees() ([]*model.WishTree, error) {
+	var trees []*model.WishTree
+	if err := s.db.Where("status = 1").Order("sort ASC, id ASC").Find(&trees).Error; err != nil {
+		return nil, err
+	}
+	return trees, nil
+}
+
 // GetWishTree 获取许愿树
 func (s *WishService) GetWishTree(treeID uint) (*model.WishTree, error) {
 	var tree model.WishTree
@@ -88,6 +97,18 @@ func (s *WishService) CreateWish(wish *model.Wish) error {
 	return s.db.Create(wish).Error
 }
 
+// GetTreeWishes 获取指定树的许愿列表
+func (s *WishService) GetTreeWishes(treeID uint) ([]*model.Wish, error) {
+	var wishes []*model.Wish
+	if err := s.db.Where("tree_id = ? AND status = 1", treeID).
+		Order("position DESC, created_at DESC").
+		Limit(100).
+		Find(&wishes).Error; err != nil {
+		return nil, err
+	}
+	return wishes, nil
+}
+
 // GetWishList 获取许愿列表
 func (s *WishService) GetWishList(treeID uint, page, pageSize int) ([]*model.Wish, int64, error) {
 	var wishes []*model.Wish