PreToolUse hooks can now rewrite tool inputs before execution

What this changes for operators

• Hook authors who returned updatedInput in PreToolUse hooks expecting rewrites to apply should re-test: prior to this fix, the original input was used; after this fix, the rewritten input is used. Verify existing hooks behave as intended after upgrade.
• Operators can now build input-sanitizing PreToolUse hooks that modify tool arguments before dispatch -- path normalization, argument masking, destination redirection.