dsh-all-gitbash: Redirecting PowerShell Execution to Git Bash on Windows

`dsh-all-gitbash` is a Windows plugin for DeepSeek Harness (DSH), designed to address the impedance mismatch when AI writes POSIX code on Windows. It reroutes execution at runtime, redirecting the execution environment from PowerShell to Git Bash to enable hot switching without a restart. The plugin provides native Bash tool registration, a command translation compatibility layer (such as path conversion), and a one-click toggle. It supports persistent installation or temporary injection, resolving the issue of models preferring Bash syntax. However, note that MSYS cannot run in a restricted sandbox; full permissions are recommended.