fix(installer): remove grep usage for Windows compatibility

[abbas-rz]

fix(installer): remove grep usage for Windows compatibility in conda channel add step

Replaced the Linux-specific grep -v 'already exists' pipe with a direct conda config --add channels conda-forge call. Conda already returns success when the channel exists, so filtering is unnecessary and broke the installer on Windows (where grep is unavailable).

Summary

This PR fixes the Windows compatibility issue in the One-Click Installer.

The installer previously ran:

conda config --add channels conda-forge 2>&1 | grep -v 'already exists'

This fails on Windows because grep is not available by default. Since
conda config --add does not error out when the channel already exists,
the filtering is unnecessary.

Changes

• Removed the grep pipe and simplified the command to:

  conda config --add channels conda-forge
  

Why This Matters

• Installer now works on Windows without requiring Git Bash or manual grep installation.
• Behavior remains correct on Linux/macOS.