Fix CJK emphasis delimiter detection in scanDelims

[awoni]

Summary

Fix emphasis delimiter detection for mixed CJK/ASCII text.

In CommonMark's scanDelims, when an emphasis closing marker ** is preceded by ASCII punctuation (e.g. %) and followed by a CJK character, right_flanking evaluates to False — causing bold to silently fail.

Example: 湾岸の**46%**を renders as plain text instead of <strong>46%</strong>.

Root Cause

CJK characters (e.g. を, の, は) are not classified as whitespace or punctuation by the spec. When lastChar='%' (punctuation) and nextChar='を' (neither whitespace nor punctuation):

right_flanking = not (isLastPunctChar and not (isNextWhiteSpace or isNextPunctChar))

evaluates to False, so the closing ** is rejected.

Fix

Treat characters above U+2E7F as punctuation for flanking delimiter checks (6 lines added to scanDelims in state_inline.py). This covers CJK Unified Ideographs, Hiragana, Katakana, Hangul, and other East Asian scripts.

Test Cases

from markdown_it import MarkdownIt
md = MarkdownIt("commonmark")

assert "<strong>" in md.render("湾岸の**46%**を供給")
assert "<strong>" in md.render("の**20〜25%**が通過する")
assert "<strong>" in md.render("日本語の**太字**テスト")
assert "<strong>" in md.render("**全部太字**")
assert "<strong>" in md.render("English **bold** test")

All pass. Existing English-only behavior is unchanged.

Note

The same bug likely exists in the JavaScript version of markdown-it.