next.js

f50c769f - fix: add backwards compat for middleware → proxy field renames (#85183)

fix: add backwards compat for middleware → proxy field renames (#85183) ### What? These config keys were recently soft-renamed with forward compatibility on the _resolved_ config object: - `experimental.proxyPrefetch` → `experimental.middlewarePrefetch` - `experimental.externalProxyRewritesResolve` → `experimental.externalMiddlewareRewritesResolve` - `skipProxyUrlNormalize` → `skipMiddlewareUrlNormalize` But there was no backwards compatibility on the resolved, which is (arguably) an undocumented breaking change. ### Why? This avoids introducing a last-minute breaking change for providers and other integrations that read the the `.next/` build output files (which is necessary until we all move to the upcoming [Adapter API](https://github.com/vercel/next.js/discussions/77740). ### How? When a new `proxy` config key is set but the old `middleware` name is not, copy the value to the old name on the *resolved* config object. This also adds test coverage for both the existing forward compat (old→new) and the new backwards compat (new→old). Co-authored-by: JJ Kasper <jj@jjsweb.site>