revert: documentation research and workflow setup (#318)

[Max17190]

Why

Return the documentation research and workflow setup changes from #318 to review before they ship further. The two workflow skills it registers are also being reverted in firecrawl/firecrawl-workflows#10, so the CLI has to stop requesting them first.

Summary

• Revert feat(skills): improve documentation research and workflow setup #318: restore the previous firecrawl-developer-index skill and remove its official documentation reference, remove firecrawl-fantasy-sports and firecrawl-job-postings from the workflow selection, and drop the related init and setup tests.
• Bump the version to 1.26.7 so the publish workflow releases the reverted CLI. 1.26.5 already exists on npm, so a plain revert would skip publishing.
• Merge and publish this before the firecrawl-workflows revert. If the catalog drops the two workflows while 1.26.6 is the latest release, firecrawl setup reports success for them without installing anything.

Test Plan

• pnpm run build, pnpm run type-check, pnpm run format:check
• pnpm test: 38 files and 684 tests passed with FIRECRAWL_API_KEY unset
• The built CLI reports 1.26.7, and the workflow selection lists 16 skills without firecrawl-fantasy-sports or firecrawl-job-postings