vinext: middleware.ts does not run for files in public/ #743

In a vinext app deployed with Void, requests for files in public/ skip middleware.ts. Cloudflare serves these files from Workers Static Assets before the Worker runs. Next.js runs middleware for every path its matcher covers, including public/ files. Therefore, on Void, a middleware auth check on /report.pdf does not protect the file.

vinext fixed this in its own Cloudflare setup (cloudflare/vinext#3217). vinext init writes run_worker_first: ["/*", "!/_next/static/*", ...] (cloudflare/vinext#3804). Void can't use the same setting: since #660, static files skip the Worker, in order to not count toward the Workers Free limit of 100,000 requests a day.

Possible approach: if the app has middleware.ts, run the Worker first only for the paths its matcher covers. Apps without middleware keep the current routing.

Worker-first routing alone is not enough though. The build wrapper sends every GET or HEAD 404 from the framework to env.ASSETS (createAssetFallback), so a file is still served when middleware returns 404 for it.

Found while working on #742.