docs: update X account manager from junhoyeo to justsisyphus (#148)

* docs: update X account manager from junhoyeo to justsisyphus

Changed the notice to reflect that @justsisyphus is now managing
oh-my-opencode updates on X instead of @_junhoyeo.

* docs: add X account manager notice to all language READMEs

Added notice about @justsisyphus managing oh-my-opencode updates
on X to Korean, Japanese, and Chinese README files.

---------

Co-authored-by: Claude <[email protected]>

Author: code-yeongyu

README.ja.md

@@ -1,3 +1,5 @@
+お知らせ: oh-my-opencodeに関するニュースは私のXアカウントで投稿していましたが、無実の罪で凍結されたため、[@justsisyphus](https://x.com/justsisyphus)が代わりに管理しています。
+
 <!-- <CENTERED SECTION FOR GITHUB DISPLAY> -->
 
 <div align="center">

README.ko.md

@@ -1,3 +1,5 @@
+공지: oh-my-opencode 관련 소식은 제 X 계정에서 올렸었는데, 억울하게 정지당해서 [@justsisyphus](https://x.com/justsisyphus)가 대신 관리하고 있습니다.
+
 <!-- <CENTERED SECTION FOR GITHUB DISPLAY> -->
 
 <div align="center">

README.md

@@ -1,4 +1,4 @@
-NOTICE: News regarding oh-my-opencode used to posted on my X account, but since it got suspended innocently, my friend [@_junhoyeo](https://x.com/_junhoyeo) will post on behalf of me. (THE GUY WHO MADE HERO IMAGE)
+NOTICE: News regarding oh-my-opencode used to be posted on my X account, but since it got suspended innocently, [@justsisyphus](https://x.com/justsisyphus) is now managing updates on behalf of me.
 
 <!-- <CENTERED SECTION FOR GITHUB DISPLAY> -->
 

README.zh-cn.md

@@ -1,3 +1,5 @@
+公告：oh-my-opencode 的相关消息之前在我的 X 账号发布，但由于账号被无辜封禁，现在由 [@justsisyphus](https://x.com/justsisyphus) 代为管理更新。
+
 <!-- <CENTERED SECTION FOR GITHUB DISPLAY> -->
 
 <div align="center">