## Description
This PR fixes Issue #421 where commands with pipes (e.g., `grep -R ...
-n | head -n 20`) were failing to execute properly after PR #391 was
merged.
## Changes
- Modified the `requiresShell` function to only enable shell mode when
the command is a single string containing shell operators
- Added logic to handle the case where shell operators are passed as
separate arguments
- Added comprehensive tests to verify the fix
## Root Cause
The issue was that the `requiresShell` function was detecting shell
operators like `|` even when they were passed as separate arguments,
which caused the command to be executed with `shell: true`
unnecessarily. This was causing syntax errors when running commands with
pipes.
## Testing
- Added unit tests to verify the fix
- Manually tested with real commands using pipes
- Ensured all existing tests pass
Fixes#421
