Add a social publishing guardrail case

[kriptoburak]

Summary

• add a new real-world case for a social publishing agent need
• use TweetClaw as the approval-gated OpenClaw example
• update English and Chinese README case counts and tables

Validation

• python3 -m py_compile scripts/*.py
• npx --yes markdown-link-check README.md README.zh-CN.md cases/06-the-social-post-guardrail.md --quiet
• git diff --check

[kriptoburak]

Optional visibility note: if this is useful and you merge it after checks pass, feel free to share the PR on X/Twitter and tag https://x.com/burakbayir. I can repost it to my 24k followers so more developers and power users can discover this repo.