Previously \\U+XXXX was in the "strip until ;" list, silently dropping
all Unicode character references (°, ±, ⌀, Ø, €, …).
Changes:
- \\U+XXXX / \\u+XXXX decode to the actual Unicode character (was stripped)
- \\S upper/lower; stacked fractions/tolerances render as "upper/lower"
or "upper^lower" instead of leaking as literal text
- \\t tab → four spaces (was leaking as literal 't')
- Unknown escapes silently consume the code char (was leaking it)
- \\M+...; DBCS multibyte — stripped (added to semicolon-arg list)
- \\X paragraph-align end marker — stripped cleanly
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>