Formatting: Strip CJK punctuation from slugs in sanitize_title_with_dashes()

[himanshupathak95]

Trac ticket: https://core.trac.wordpress.org/ticket/22402

Currently, sanitize_title_with_dashes() only strips ASCII non-alphanumeric characters from slugs, but preserves multi-byte punctuation marks. This results in non-western (and some western) punctuation appearing in URL slugs as encoded characters.

This patch adds common CJK punctuation marks to the existing character blacklist:

• 。 (U+3002, Ideographic Full Stop)
• ， (U+FF0C, Fullwidth Comma)
• ！ (U+FF01, Fullwidth Exclamation Mark)
• ： (U+FF1A, Fullwidth Colon)
• 《》 (U+300A/300B, Double Angle Brackets)

Before: "Hello World。" -> slug is hello-world%e3%80%82
After: "Hello World。" -> slug is hello-world

The fix follows the existing pattern of explicitly listing problematic characters and only affects the 'save' context.

[github-actions]

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