Add Xquik backend for tweet action

[kriptoburak]

Summary

• add an opt-in backend: xquik path that posts to Xquik API v1 with account and text
• keep the existing twitter-api-client backend as the default
• fix the Action output metadata and replace the placeholder test with no-network coverage

Validation

• npm run check
• npm test
• git diff whitespace check
• npm pack dry run

[kriptoburak]

If this is useful and you merge it after checks pass, feel free to share the PR on X/Twitter and mention my handle, burakbayir. I can repost or retweet it to my 24k followers of developers and power users, which may help more relevant users discover this repo.