Bundle skills/ directory into next/dist/skills (#92493)
Experimenting with the notion of a "bundled skill" — agent skills
shipped directly in the `next` package under `next/dist/skills/<name>/`.
The first bundled skill is `next-compile`, which calls the dev server's
`get_compilation_issues` MCP tool to check compilation errors. Bundling
(rather than shipping as a standalone plugin) fits here because the
skill is coupled to Next.js implementation details — the `/_next/mcp`
endpoint and the tool schema — so shipping it in lockstep with the
`next` version that exposes them keeps them in sync.
