fix(supervisor): quote space-containing args in PowerShell Start-Process on Windows

[samclark2015]

Fixes #14671

When kernelSupervisor.shutdownTimeout is changed from the default (immediately) on Windows, Positron launches the Kallichore server via PowerShell's Start-Process. PowerShell joins -ArgumentList array elements with spaces when building the cmd.exe command line, so a path like c:\Program Files\...\kcserver.exe is split at the space and cmd.exe tries to run c:\Program — producing the 'c:\Program' is not recognized error.

The fix wraps arguments that contain spaces in double-quotes within the PowerShell array so cmd.exe treats each path as a single token. The batch wrapper is also updated to use %~1 (strips surrounding double-quotes) when assigning the output file path, for defensive correctness.

Release Notes

New Features

• N/A

Bug Fixes

• Fix supervisor failing to start when kernelSupervisor.shutdownTimeout is non-default on Windows installations with spaces in the path (supervisor: failure when kernelSupervisor.shutdownTimeout is changed from default on Windows installations with spaces in the path #14671)

Validation Steps

@:win @:sessions

This fix is Windows-only and requires an installation in a path containing spaces (e.g. C:\Program Files\Positron\):

1. Install Positron to a path with spaces
2. Set kernelSupervisor.shutdownTimeout to when idle (or any non-immediately value)
3. Restart Positron
4. Start an R or Python console session — it should start without error

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:win @:sessions @:console @:interpreter

Why these tags?

Tag	Source
@:critical	Always runs (required)
@:win	PR description
@:sessions	PR description
@:console	Changed files
@:interpreter	Changed files

More on automatic tags from changed files.

^{readme  valid tags}