refactor: space页面改为卡片式关注列表布局

- 重写 space/index.html：左右分栏，左侧导航栏 + 右侧卡片网格
- 自己空间：显示全部关注用户卡片（头像/用户名/简介/已关注标签）+ 设置入口
- 他人空间：简化侧栏（Ta的关注/粉丝），隐私关闭时显示空状态插图
- Model UserFollow 新增头像/简介联表字段
- Repository ListFollowing/ListFollowers SELECT 增加 avatar/bio
- Controller ShowSpace 注入 FollowService，获取关注列表数据
- space.css 完全重写为卡片网格布局 + 响应式适配
- follow.css 清理旧 .follow-btn/.follow-links 无用样式

internal/repository/follow_repo.go

@@ -56,7 +56,7 @@ func (r *FollowRepo) CountFollowing(userID uint) (int64, error) {
 	return count, err
 }
 
-// ListFollowers 粉丝列表（分页，JOIN users 获取用户名）
+// ListFollowers 粉丝列表（分页，JOIN users 获取用户名、头像、简介）
 func (r *FollowRepo) ListFollowers(userID uint, offset, limit int) ([]model.UserFollow, int64, error) {
 	var total int64
 	if err := r.db.Model(&model.UserFollow{}).Where("followee_id = ?", userID).Count(&total).Error; err != nil {
@@ -64,7 +64,7 @@ func (r *FollowRepo) ListFollowers(userID uint, offset, limit int) ([]model.User
 	}
 	var items []model.UserFollow
 	err := r.db.Table("user_follows").
-		Select("user_follows.*, u.username AS follower_username").
+		Select("user_follows.*, u.username AS follower_username, u.avatar AS follower_avatar, u.bio AS follower_bio").
 		Joins("INNER JOIN users u ON u.uid = user_follows.follower_id").
 		Where("user_follows.followee_id = ?", userID).
 		Order("user_follows.created_at DESC").
@@ -73,7 +73,7 @@ func (r *FollowRepo) ListFollowers(userID uint, offset, limit int) ([]model.User
 	return items, total, err
 }
 
-// ListFollowing 关注列表（分页，JOIN users 获取用户名）
+// ListFollowing 关注列表（分页，JOIN users 获取用户名、头像、简介）
 func (r *FollowRepo) ListFollowing(userID uint, offset, limit int) ([]model.UserFollow, int64, error) {
 	var total int64
 	if err := r.db.Model(&model.UserFollow{}).Where("follower_id = ?", userID).Count(&total).Error; err != nil {
@@ -81,7 +81,7 @@ func (r *FollowRepo) ListFollowing(userID uint, offset, limit int) ([]model.User
 	}
 	var items []model.UserFollow
 	err := r.db.Table("user_follows").
-		Select("user_follows.*, u.username AS followee_username").
+		Select("user_follows.*, u.username AS followee_username, u.avatar AS followee_avatar, u.bio AS followee_bio").
 		Joins("INNER JOIN users u ON u.uid = user_follows.followee_id").
 		Where("user_follows.follower_id = ?", userID).
 		Order("user_follows.created_at DESC").