Replace POSIX shell-based hub fixtures with a helper executable that resolves
correctly on both Windows and Linux. This prevents Windows tests from falling
through to a real hub.exe and hanging on network access.
Document PowerShell installation and Windows path usage, require the .exe
suffix for explicit Windows build output, and ignore generated binaries.
Walk a workspace for Git repositories, including intentionally nested repos,
while pruning dependency caches and build output directories.
Inspect each branch, remote, operation state, and porcelain status before
running hub sync. Recheck safety immediately before mutation, keep nested
repositories from falsely dirtying their parent, and support concurrency,
exclusions, strict mode, timeouts, JSON output, and explicit confirmation.
LyAhn