findWorkflowInParents() and discoverProjectWorkflows() now check for .git
(directory or file) after scanning the current directory for workflows and
before moving to the parent. This prevents traversal from escaping the
repository root and picking up unrelated .workflow/ directories in parent
directories.
Both .git as a directory (normal clone) and .git as a file (git worktree)
are treated as boundaries.
Fixes#168
xiaoju