Detect SCIP installation in conda environment if SCIPOPTDIR is not defined

[mmghannam]

To make it a bit easier to develop pyscipopt for some people. Including me :)

[Joao-Dionisio]

I assume you tested this, so all good on my end! Just bringing copilot over, just in case.

[Copilot]

Pull Request Overview

This PR enhances the setup script to automatically detect and use conda environments when SCIPOPTDIR is not explicitly set, improving the installation experience for conda users.

• Added automatic conda environment detection via the CONDA_PREFIX environment variable
• Refactored the fallback installation logic to prioritize conda environments over global installations
• Cleaned up redundant platform checks for Windows

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
setup.py	Added conda environment detection logic and refactored the installation path resolution to check for conda first, then fall back to global installations
INSTALL.md	Added documentation explaining the new automatic conda environment detection behavior
CHANGELOG.md	Documented the new feature for conda environment detection

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[Copilot]

The validation only checks for the existence of the include directory but not the lib directory. This could lead to setup failures later when the library path is used. Consider also validating that os.path.join(conda_prefix, 'lib') exists before committing to use the conda environment.

Suggested change

	if conda_prefix and os.path.exists(os.path.join(conda_prefix, "include")):
	if (
	conda_prefix
	and os.path.exists(os.path.join(conda_prefix, "include"))
	and os.path.exists(os.path.join(conda_prefix, "lib"))
	):

[mmghannam]

I assume you tested this, so all good on my end! Just bringing copilot over, just in case.

Yup tested against the latest conda package of scip 9.2.4