Summary

- Adds Windows agent terminal sandboxing by routing commands through WSL
and Bubblewrap.
- Supports native Windows and WSL project paths, including elevated
write grants for WSL paths.
- Shows a confirmation prompt to turn off sandboxing when WSL sandbox
setup is unavailable.

This builds on the work in the sandbox-linux branch.

Closes AI-376

Release Notes:

- Added Windows terminal sandboxing for agent commands when sandboxing
is enabled.

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Co-authored-by: cameron <cameron.studdstreet@gmail.com>
Co-authored-by: Richard Feldman <oss@rtfeldman.com>
Co-authored-by: zed-zippy[bot] <234243425+zed-zippy[bot]@users.noreply.github.com>