[skills] Sync routing-middleware with current docs

[vercel-gh-bot-3]

• Stale claim: frontmatter cited https://nextjs.org/docs/app/building-your-application/routing/middleware, which now redirects.
  Correction: updated to the canonical URL https://nextjs.org/docs/app/api-reference/file-conventions/proxy. Next.js deprecated the middleware file convention and renamed it to proxy (as the skill body itself already correctly documents in its "CRITICAL: Middleware Disambiguation" section).
  Source: https://nextjs.org/docs/app/api-reference/file-conventions/proxy (version 16.3.6, lastUpdated 2026-09-07) — "The middleware file convention is deprecated and has been renamed to proxy" and version history: "v16.0.0 | Middleware is deprecated and renamed to Proxy."

Verification: run_plugin_checks — build ✅, typecheck ✅, validate ✅, test ✅ (1030 pass / 0 fail).

Test updates: none.

Upstream contradictions: n/a (standalone skill).

Not changed: the rest of the skill body (proxy.entrypoint, disambiguation table, CVE-2025-29927 note, matcher config, request limits, CDN routing mechanisms) was checked against https://vercel.com/docs/routing-middleware, /routing-middleware/api, and /routing-middleware/getting-started (all unchanged since the skill's last commit) and still matches current docs.

Opened automatically by the vercel-plugin drift agent. Review before merge.

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Drift scan update 2026-09-24

• Stale claim: metadata.docs cited https://nextjs.org/docs/app/building-your-application/routing/middleware, which now redirects. Correction: updated the citation to the canonical URL https://nextjs.org/docs/app/api-reference/file-conventions/proxy (redirect, 200, canonicalUrl: https://nextjs.org/docs/app/api-reference/file-conventions/proxy).
• Stale claim: "Migration codemod: npx @next/codemod@latest middleware-to-proxy". Correction: the Next.js docs give the command as npx @next/codemod@canary middleware-to-proxy . (uses the @canary dist-tag and a required target-directory argument, not @latest with no target). Source: https://nextjs.org/docs/app/api-reference/file-conventions/proxy, section "How to Migrate": "Next.js provides a codemod to migrate from middleware.ts to proxy.ts. You can run the following command to migrate: npx @next/codemod@canary middleware-to-proxy ."

Verification: run_plugin_checks — build, typecheck, validate, and test all passed (1030 pass, 0 fail).

Test updates: none needed.

Upstream contradictions: n/a (standalone skill).

Not changed:

• Bun runtime claims ("~28% lower latency in CPU-bound workloads", "Public Beta", "supports Next.js, Express, Hono, and Nitro") are supported by https://vercel.com/blog/bun-runtime-on-vercel-functions ("Bun reduced average latency by 28% in CPU-bound Next.js rendering workloads compared to Node.js"; "available in Public Beta") rather than a docs page, so left as-is — no drift found.
• "Project-level routes (added March 2026) ... Available on all plans" confirmed by https://vercel.com/changelog/vercels-cdn-now-supports-updating-routing-rules-without-a-new-deployment (Published March 5, 2026: "Project-level routes are available on all plans starting today").
• "8 dedicated endpoints" for the project routes REST API confirmed by counting the documented /v1/projects/{projectId}/routes endpoints (get, add, stage, edit, delete, get-versions, promote/restore/discard, plus the routes root) on vercel.com/docs/rest-api/project-routes/*.
• @vercel/global-config package and get() example confirmed against https://vercel.com/docs/global-config/global-config-sdk.
• NextRequest.geo/NextRequest.ip removal claim confirmed consistent with current https://nextjs.org/docs/app/api-reference/functions/next-request (no geo/ip members documented).

Opened automatically by the vercel-plugin drift agent. Review before merge.