The previous regex approach with \x{00A0} wasn't reliably catching all
nbsp-separated publisher names (e.g., "UC Santa Cruz" on article 19).
Switched to strrpos-based string search which is simpler and avoids
potential PCRE/UTF-8 edge cases with multibyte characters.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>