Feature request: integrate the exptostd linter

Feature request: integrate the exptostd linter: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). There's a small static-analysis tool, exptostd (https://github.com/ldez/exptostd), that flags usages of functions from golang.org/x/exp/maps and golang.org/x/exp/slices…

The task

There's a small static-analysis tool, [`exptostd`](https://github.com/ldez/exptostd), that flags usages of functions from `golang.org/x/exp/maps` and `golang.org/x/exp/slices` that can now be replaced by their counterparts in the Go standard library (`maps`, `slices`, and the `clear` builtin) since Go 1.21 / 1.23.

Part of FineEnvs/MiMo-V2.6-RL-harbor-code.