- new `script/warp_sudo`: echoes each privileged command, prompts
`[y/N]` from `/dev/tty`, shells to real `sudo` on confirm.
`WARP_BOOTSTRAP_YES=1` or non-tty stdin skips.
- `script/bootstrap`: static `--help` install list dropped. `-y`/`--yes`
exports `WARP_BOOTSTRAP_YES=1` for children.
- ten direct `sudo` call-sites in `script/{macos,linux}/bootstrap` +
`script/linux/install_{build,runtime,test}_deps` switched to
`warp_sudo`. windows unchanged.
- `README.md`: short "what `./script/bootstrap` does" subsection
pointing at the platform scripts as the source of truth.
closes#9421.