next.js

ec28a4fd - Remove `experimental.useNodeStreams` flag as it's enabled (#93938)

Remove `experimental.useNodeStreams` flag as it's enabled (#93938) ### What? Remove `experimental.useNodeStreams` from the public config surface and make Node streams always-on for Node.js App Router rendering. The smaller default-on change and dedicated CI cleanup landed in #94311. The standalone compatibility update landed separately in #94347. ### Why? Node streams are now the default Node.js runtime rendering path, so the opt-in config and runtime selection plumbing are stale. Edge bundles continue to use the web-stream path because Node streams are unavailable there. ### How? - Define `__NEXT_USE_NODE_STREAMS` as true for Node.js app runtime bundles and false for edge user bundles. - Remove config, schema, runtime, export, and server plumbing for `experimental.useNodeStreams`. - Delete the obsolete env-precedence fixture. - Clean benchmark docs and scripts that still set or compare `experimental.useNodeStreams`. ### Verification - `pnpm --filter=next types` - `pnpm build-all` <!-- NEXT_JS_LLM_PR -->