docs: add optional TweetClaw launch signals

[kriptoburak]

Summary

• Add an optional TweetClaw note to the README skills section for authors running AuthorClaw beside OpenClaw.
• Extend the marketing-research skill with an X/Twitter launch-signal workflow.
• Keep TweetClaw output scoped to reviewed summaries, tweet URLs or IDs, audience notes, and follow-up tasks.

Checks

• Confirmed the repo has no existing TweetClaw, Xquik, ClawHub, or package mentions.
• Reviewed all open and closed issues and PRs for duplicate TweetClaw or Xquik history.
• Ran git diff --check.
• Verified https://github.com/Xquik-dev/tweetclaw returns 200.
• Verified @xquik/tweetclaw is published as 1.6.31 and openclaw as 2026.5.12.
• Ran npm ci --ignore-scripts --no-audit --no-fund.
• Ran npm run build.