Add Xquik plugin

[kriptoburak]

Summary

• Add a partner-built Xquik plugin package.
• Configure the authenticated Xquik MCP server with an XQUIK_API_KEY environment variable.
• Register the plugin in the marketplace and include one X research skill.

Validation

• Confirmed no existing Xquik plugin, PR, or recent issue.
• Confirmed root Apache-2.0 license and plugin file structure.
• Validated marketplace, plugin, and MCP JSON with jq.
• Checked public Xquik docs, website, GitHub repo, and npm package metadata.
• Ran diff whitespace validation.

[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.