Add X/Twitter source packet guidance

[kriptoburak]

Summary

• Add optional X/Twitter source-packet guidance for Mentor Mode social fragments.
• Mention TweetClaw as an optional OpenClaw or npm collection tool while keeping Digital Clone responsible for evidence grading, corpus refinement, negative-space analysis, and verification.
• Remove the stale content-publisher GitHub link target after the public repo returned 404 and no replacement appeared under the owner account.

Validation

• git diff --check
• npx --yes markdown-link-check README.md SKILL.md --quiet
• SKILL.md frontmatter fence check
• TweetClaw GitHub URL probe
• npm registry metadata check for @xquik/tweetclaw
• OpenClaw docs check for npm:, npm-pack:, plugin update, and runtime inspect guidance