实现删除主题操作

[github-actions]

https://api.github.com/bangumi/frontend/blob/7ce2f190e1aa707aa232d8b4cda9689dce34491c/packages/website/src/pages/index/group/topic/[id]/index.tsx#L79

              <RichContent bbcode={topicDetail.text} />
              {user && (
                <div className={styles.topicActions}>
                  <CommentActions
                    showText
                    id={topicDetail.id}
                    isAuthor={user.id === topicDetail.creator.id}
                    onReply={startReply}
                    // TODO: 实现删除主题操作
                  />
                </div>
              )}
            </div>

[github-actions]

Closed in 45ca3e6.