[RFC]: add missing single precision `nan` modules for `stats/strided`

### Description

This RFC proposes to add missing single precision `nan` modules for `stats/strided`, which include :

- [ ] snanmeanpw
- [ ] snanmeankbn
- [ ] snanmeankbn2
- [ ] snanmeanli
- [ ] snanmeanlipw
- [ ] snanmeanstdev
- [ ] snanmeanstdevpn
- [ ] snanmeanvar
- [ ] snanmeanvarpn
- [ ] sdsnanmean
- [ ] sdsnanmeanpn
- [ ] sdsnanmeanwd
- [ ] sdsnanmeanpw
- [ ] snanvariance
- [ ] snanvariancech
- [ ] snanvariancepn
- [ ] snanvariancetk
- [ ] snanvariancewd
- [ ] snanvarianceyc
- [ ] snanstdev
- [ ] snanstdevch
- [ ] snanstdevpn
- [ ] snanstdevtk
- [ ] snanstdevwd
- [ ] snanstdevyc
- [ ] snansem
- [ ] snansemch
- [ ] snansempn
- [ ] snansemtk
- [ ] snansemwd
- [ ] snansemyc
- [ ] snanrangeabs
- [ ] snanmidrangeabs
- [ ] snancumax
- [ ] snancumaxabs
- [ ] snancumin
- [ ] snancuminabs

NOTE: Priority is top to bottom.

### Related Issues

None

### Questions

1. How many packages do we really need ? ( I have already eliminate those packages which not useful or not feasible )
2. What should be the priority of all the modules mentioned here?

### Other

No.

### Checklist

- [x] I have read and understood the [Code of Conduct](https://github.com/stdlib-js/stdlib/blob/develop/CODE_OF_CONDUCT.md).
- [x] Searched for existing issues and pull requests.
- [x] The issue name begins with `RFC:`.

Start by surveying the existing stats/strided modules and the listed single-precision nan variants to understand the project’s conventions. No specific file, test, or entry point is named in the issue, so first resolve the proposed package count and priority with maintainers. Done means implementing the agreed subset of all listed modules with matching coverage.

索引モデルが issue の本文から書いたものです。