docs: update Last Updated date and Claude Code version across all files

Update all documentation footers from generic "April 2026 / 2.1+" to
the specific sync date (April 9, 2026) and documented version (2.3.0).
Also add version/date footers to zh/CATALOG.md and
zh/01-slash-commands/README.md which were missing them.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

zh/01-slash-commands/README.md

@@ -548,4 +548,9 @@ allowed-tools: Bash(npm *), Bash(git *)
 
 ---
 
+**最后更新**: 2026 年 4 月 9 日
+**Claude Code 版本**: 2.3.0
+
+---
+
 *Claude How To 指南系列的一部分*