Handle zsh process substitution correctly

[mrubens]

Thanks @MaccariTA for reporting this issue.

Important

Add detection for zsh process substitution in command validation to flag as dangerous.

• Behavior:
  • containsDangerousSubstitution in command-validation.ts now detects zsh process substitution =() as dangerous.
  • Commands with zsh process substitution are flagged to require user approval.
• Tests:
  • Added tests in command-validation.spec.ts to verify detection of zsh process substitution patterns like ls =(open -a Calculator).
  • Ensures various forms of zsh process substitution are correctly identified as dangerous.
  • Tests confirm that commands with these patterns are not auto-approved.

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[roomote]

Thank you for your contribution! This PR adds important security protection against zsh process substitution. The implementation is clean and follows existing patterns well. I've left a few minor suggestions inline for your consideration.

[roomote]

Consider handling edge cases in the regex pattern. The current pattern /=\([^)]+\)/ requires at least one character inside the parentheses. While =() with empty parentheses is invalid zsh syntax, you might want to consider if the pattern should also catch this for completeness:

Suggested change

	const zshProcessSubstitution = /=\([^)]+\)/.test(source)
	const zshProcessSubstitution = /=\([^)]*\)/.test(source)

This would use * instead of + to match zero or more characters.

[roomote]

Good comprehensive test coverage! Is it intentional that this test case duplicates the one at line 351? If so, perhaps add a comment noting that line 351 specifically tests the reported exploit, while this section tests various forms more generally.

[roomote]

The pattern will match =() anywhere in the string, including potentially in contexts where it might not be process substitution (e.g., within strings or comments). However, this approach is consistent with how other dangerous patterns are detected in this module, appropriately favoring security over precision. Just noting this for awareness.