Add tokrepo-search skill

[henu-wang]

This adds a native tokrepo-search skill for GitHub Copilot.

Why it fits:

• helps users discover installable skills, MCP servers, prompts, and workflows instead of recreating them from scratch
• uses a simple skill folder under skills/ and updates the generated skills index entry
• keeps the guidance practical: search, shortlist results, and provide install commands

I also ran npm run skill:validate locally and the new skill passed validation.

Happy to adjust wording if you want it framed more narrowly around Copilot workflows.

[aaronpowell]

It looks like you've incorrectly branched from the main branch not staged, and as a result all the materialised plugins are included in this PR.

You can attempt to fix this with a rebase:

git fetch origin staged
git rebase --onto origin/staged origin/main <branch name>
git push --force-with-lease

If that does not resolve it, you can run npm run plugin:clean which will delete the materialised plugins and you can commit that change.