Replace make with just as the task runner

[ecomodeller]

Summary

• Replace Makefile with justfile for cross-platform compatibility (fixes Windows CI)
• Update all CI workflows to install and use just via extractions/setup-just@v3
• Update CONTRIBUTING.md and CLAUDE.md to reference just instead of make

[otzi5300]

on windows using powershell.

installed just using:
uv tool install rust-just

then run "uv run just test", which gave error:
error: Recipe test could not be run because just could not find the shell: program not found

adding "set shell := ["powershell.exe", "-NoLogo", "-Command"]" at the top of the justfile fixed it.

it would be Is there any way of automatically detecting windows and setting appropriate configs. Or should this be done by developer using env vars.

Otherwhise seems to work really nice on windows using uv.

[otzi5300]

Seems to work fine but see comment about setting just to work with shell instead of sh