Tag-spoofing scrub now matches Unicode look-alike and case-folded spellings

Claude Code scrubs text that tries to pass itself off as one of its own protected tags, such as a fake <channel ... opener. The scrub, createTagFormScrub, now converts non-ASCII characters and mixed capitals to plain lowercase ASCII before comparing names. This means look-alike letters from other alphabets and unusual capitalisation are caught too. A matching fake tag has its opening changed to <\, so it no longer reads as a tag.