Better reflect why this button is needed.

x-ref: [slack
thread](https://vercel.slack.com/archives/C04A1276AGK/p1748977699699439?thread_ts=1748886481.971709&cid=C04A1276AGK)

---------

Co-authored-by: Zack Tanner <[email protected]>

Style change in #80097 affected
style when adding the "Development Section" at
#80072. Therefore add the style
back to the section titles, and use "General" for the existing
preferernces.

| Before | After |
|--------|--------|
| ![CleanShot 2025-06-03 at 21 39
30@2x](https://github.com/user-attachments/assets/130825a9-6540-4c4b-ba1b-4c830e04382a)
| ![CleanShot 2025-06-03 at 21 39
17@2x](https://github.com/user-attachments/assets/3dc1444d-1588-4e4c-973a-ace88d501c95)
|

…0117)

This is a prerequisite for using https://github.com/boshen/cargo-shear, which uses `--all-features`. This also avoids some noise in Rust Analyzer, which also uses `--all-features`.

Fixes failing assertions related to the forked React 18 tests.

[x-ref](https://github.com/vercel/next.js/actions/runs/15417191195/job/43385564776#step:34:533)

When you use sync IO in the client in a way that needs to be fixed we
currently still just provide you with the explanation for server
components. The fixes when sync IO happens in the client are not the
same as when they happen in a server component so this update adds
client specific documentation for these situations.

Namely, the key difference is that on the server you can add caching
through "use cache" and this is not available to you in the client. sync
IO in general is (going to be) allowed in client components broadly as
long as Next.js has a fallback UI to prerender. This means that "fixing"
sync IO access in the client will usually be solved by wrapping in a
Suspense boundary. The alternative is to move the sync IO out of render
or move it to the server where it can be cached.

…80121)

Remove unused dependencies to (hopefully) speed up the build.

https://github.com/boshen/cargo-shear

```
$ cargo shear --expand --exclude=wasm
Analyzing /home/bgw.linux/next.js

No unused dependencies!
```