dsh-tool-gitbash: Git Bash Utility Plugin for Windows

dsh-tool-gitbash is a DSH tool plugin designed for Windows environments, aimed at providing Git Bash execution capability for users who do not have WSL but have Git for Windows installed. This plugin registers the `gitbash` tool and utilizes the system's built-in `bash.exe` to replace native pwsh or WSL bash, eliminating the need for a WSL environment. Its core features include automatic detection of multiple installation paths, file sandbox mode, timeout control (default 120 seconds, maximum 600 seconds), output truncation, and background task support. Background execution functionality is only exposed when specific configuration is enabled, and sandbox permission escalation requires simultaneous satisfaction of `sandbox_permissions` and `justification`.