Improve cross-platform development setup (solver path handling + dependency conflict)

[parthdagia05]

Closes #10

Improve Cross-Platform Development Setup (macOS/Linux)

Overview

This PR addresses two issues encountered while attempting to run MUIO from source on macOS (Apple Silicon):

1. Hard-coded solver paths for non-Windows systems prevented standard macOS/Linux installations from working.
2. An incompatible dependency pin in requirements.txt prevented clean installation in a fresh virtual environment.

Together, these issues block cross-platform development workflows. This PR resolves both while preserving existing Windows behavior.

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1. Cross-Platform Solver Path Resolution

Problem

OsemosysClass.py previously defined solver directories using OS-specific hard-coded paths for non-Windows systems (e.g., glpk-4.65/w64, Cbc-2.10-osx10.15-x86_64-gcc9/bin).

These paths:

• Do not match standard macOS/Linux installations
• Are not compatible with Apple Silicon
• Assume bundled solver binaries that are not present in the repository
• Prevent running the application from source without manual modification

Solution

Solver path resolution has been centralized in Config.py with the following priority:

1. Environment variable override:
   • MUIO_GLPK_PATH
   • MUIO_CBC_PATH
2. Windows default (existing behavior preserved)
3. PATH-based discovery for macOS/Linux using:

shutil.which("glpsol")
shutil.which("cbc")