* fix(middleware-runtime): normalize trailing slash on plain-URL redirect locations
When middleware does NextResponse.redirect(new URL('/x', req.url)), the
Location header bypasses NextURL._applyTrailingSlash() and was emitted
verbatim even when trailingSlash config required normalization.
After relativizeLocation(), apply normalizeTrailingSlashPathname() to the
pathname of same-origin redirect Locations when trailingSlash is configured.
File-extension paths (e.g. /file.css) are correctly exempted by the existing
FILE_LIKE_PATHNAME_RE guard inside normalizeTrailingSlashPathname.
Adds 3 new tests covering the plain-URL redirect gap (trailingSlash: true,
trailingSlash: false, file-extension exemption).
Fixes#1332
* fix(tests): use concise arrow functions to satisfy arrow-body-style lint rule
* ci: retrigger CI
* ci: retrigger CI
* fix(middleware-runtime): use plain add/strip for redirect Location trailing slash
Replaces normalizeTrailingSlashPathname (the filesystem-routing normalizer,
which exempts /api, file-extension paths, and /.well-known) with the same
plain add/strip rule used by NextURL._applyTrailingSlash and Next.js's
formatNextPathnameInfo: only the root path is exempt.
This makes plain-new-URL() redirects consistent with NextURL-based redirects
and matches Next.js behavior, where a trailingSlash: true redirect to /file.css
produces /file.css/ rather than keeping the path unchanged.
Plumb `trailingSlash` from the resolved next.config into NextURL via
NextRequest, so `NextResponse.redirect(request.nextUrl)` (and any other
stringification of a NextURL) emits a Location header that matches the
user's slash policy. Mirrors Next.js's `formatNextPathnameInfo`.
Pre-route trailing-slash normalization (e.g. `/foo` -> `/foo/` when
trailingSlash:true) already runs at every entry point via
`normalizeTrailingSlash` in request-pipeline. This commit closes the
remaining gap by making redirect Locations produced from inside
middleware (the common one-hop `request.nextUrl` redirect pattern in
the Next.js middleware-trailing-slash fixture) carry the slash too.
Refs #1332. Sub-problem 3 (shallow navigation triggering a server
roundtrip) is a separate Pages Router client-side concern and deferred
as follow-up.
James Anderson