docs: add TweetClaw social monitor path

[kriptoburak]

Summary

• Add TweetClaw as an optional X/Twitter monitoring plugin for the existing social-monitor use case.
• Include the canonical OpenClaw install command for @xquik/tweetclaw.
• Keep n8n webhooks as the handoff point for summarized X/Twitter signals.

Validation

• git diff --check
• Added-line dash and sensitive-string scans
• README link sweep, with only pre-existing local, third-party, or bot-protected blockers outside this edit
• npm view @xquik/tweetclaw version returned 1.6.31