Improve handling of quoting and escaping for PowerShell commands

I keep seeing commands fail because of quote nesting, regex escaping, variable interpolation edge cases (like variables before :), or cross-shell wrapping (PowerShell -> ssh -> bash/zsh). The result is parse errors, wrong arguments being passed, or commands that behave differently from intended.

What would help most:

• Safer default command patterns for PowerShell (fewer fragile one-liners)
• Better handling of nested quoting/escaping
• Better treatment of cross-shell command boundaries
• Basic syntax sanity checks before executing generated PowerShell commands