fix: app-page URL normalization (#91121)
## Summary
Fix an App Router request normalization gap where app-page route-module
requests could keep internal RSC/segment-prefetch URLs in `req.url`.
This could leak paths like:
- `.../.segments/_tree.segment.rsc`
- `.../__PAGE__.segment.rsc`
into App Router render state and surface through `usePathname()` during
server rendering.
## What changed
- Normalize `req.url` in the app-page route-module path after `.rsc` and
`.segments/*.segment.rsc` pathname normalization.
## Why
`base-server` already keeps `req.url` in sync after RSC normalization
([ref](https://github.com/vercel/next.js/blob/5e11e67759fa38fe67f70790d7bba8c9ff9ba5fd/packages/next/src/server/base-server.ts#L676-L680)),
but the app-page route-module path only updated `parsedUrl.pathname`.
Since App Router render state seeds its canonical URL from `req.url`,
that desync could cause internal segment-prefetch paths to be treated as
the current pathname.
