Add automatic Berkeley Mono font installation

- Install.sh now downloads Berkeley Mono from static.due.ren
- Downloads all 4 variants: Regular, Bold, Oblique, Bold-Oblique
- Updated documentation to reflect automatic installation
- Removed manual installation notes from QUICK_INSTALL.md
- Berkeley Mono now included in default font installation list

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.adoc

@@ -108,7 +108,7 @@ Visit https://install.due.ren to build a custom installer with your preferred so
 * Barlow - Google Font (full family)
 * Barlow Semi Condensed - Google Font (full family)
 * Poppins - Google Font (full family)
-* Berkeley Mono - Commercial font (must purchase separately)
+* Berkeley Mono - Full family (Regular, Bold, Oblique, Bold-Oblique)
 
 == Customization