docs: add TweetClaw companion workflow

[kriptoburak]

Summary

• Add a focused companion workflow note for using TweetClaw beside HelloAgent when an OpenClaw assistant needs X/Twitter automation.
• Link the TweetClaw GitHub repo, npm package, and ClawHub listing.
• Add the xquik.com NHS Agentic Readiness badge to the existing badge row because the new companion workflow depends on xquik.com.

Validation

• npm ci --ignore-scripts
• npm run typecheck
• npm run build
• npm run test:smoke
• npm pack --dry-run --json
• git diff --check
• changed-diff credential scan