Do not enforce PowerShell on Windows

[TWiStErRob]

Describe the bug

I have a perfectly capable cmd terminal, running copilot in it is incapable of running for example gradlew. That command does not require a powershell, it's a simple batch file.

Affected version

0.0.392 Commit: cefb35e

Steps to reproduce the behavior

copilot -i "Run gradlew build and fix errors"

Expected behavior

Just works, regardless of powershell being installed or not.

Additional context

No response

[TWiStErRob]

I installed latest powershell from the provided link and I still get:

 ❯ run gradlew compileKotlin and fix all errors.

 ◐ The user wants me to:
   1. Run `gradlew compileKotlin`
   2. Fix any compilation errors

   Let me start by running the compilation and see what errors we get.

 ● I'll run the Kotlin compilation and fix any errors until it passes.

 ✗ Run Kotlin compilation
   $ .\gradlew compileKotlin
   <exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell. Error: Error: Command failed: pwsh.exe --version
   'pwsh.exe' is not recognized as an internal or external command,
   operable program or batch file.
   >

 ✗ Run Kotlin compilation with Windows PowerShell
   $ powershell -Command ".\gradlew.bat compileKotlin"
   <exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell. Error: Error: Command failed: pwsh.exe --version
   'pwsh.exe' is not recognized as an internal or external command,
   operable program or batch file.
   >

 ✗ Run Kotlin compilation using cmd
   $ cmd /c gradlew.bat compileKotlin
   <exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell. Error: Error: Command failed: pwsh.exe --version
   'pwsh.exe' is not recognized as an internal or external command,
   operable program or batch file.
   >

 ● Let me try a different approach:

 ✗ Check for PowerShell availability
   $ Get-Command powershell
   <exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell. Error: Error: Command failed: pwsh.exe --version
   'pwsh.exe' is not recognized as an internal or external command,
   operable program or batch file.
   >

 ● I'm encountering an issue with PowerShell. Let me check if I can use Python to run the command:

 ✗ Run gradle via Python subprocess
   $ python -c "import subprocess; subprocess.run(['gradlew.bat', 'compileKotlin'])"
   <exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell. Error: Error: Command failed: pwsh.exe --version
   'pwsh.exe' is not recognized as an internal or external command,
   operable program or batch file.
   >

 ● It appears there's a system configuration issue preventing me from executing commands. The error indicates PowerShell 6+ (pwsh) is not available on your system.

love the fresh user experience, thank you!