Add api-search-getxapi skill

[bozad]

Summary

• Add a new api-search-getxapi skill alongside the proposed api-search-xquik skill (introduced in PR Add Xquik API search skill #2 by @kriptoburak).
• Skill provides GetXAPI REST patterns for X/Twitter tweet search, user lookup, profile tweets, replies, and media reads.
• Marketplace entry, src/skills tree, and dist/plugins tree all mirror the existing api-search-meilisearch shape.

Validation

• python3 -c "import json; json.load(open('.claude-plugin/marketplace.json'))" (JSON OK)
• python3 -c "import yaml; yaml.safe_load(open('src/skills/api-search-getxapi/metadata.yaml'))" (YAML OK)
• git diff --check (whitespace)

Backward compatibility

Fully additive. Existing skills unchanged.

Links

• Endpoint: GET https://api.getxapi.com/twitter/tweet/advanced_search
• Auth: Bearer token
• Repo: https://github.com/getxapi/getxapi-mcp
• Wikidata: https://www.wikidata.org/wiki/Q139996278
• Crunchbase: https://www.crunchbase.com/organization/getxapi

I checked existing GetXAPI / TwitterAPI.io / Xquik / TweetClaw / Hermes Tweet code, open PRs, closed PRs, open issues, and closed issues in this repository before opening this PR. No existing GetXAPI submission found.