Complete Italian translations

[meska]

Summary

• complete all currently empty Italian translations
• review and replace fuzzy or mismatched translations
• keep established technical and ebook terminology in English where that is clearer in the CWA interface
• add translations for the latest duplicate-index and auto-resolution UI strings on main

Validation

• 1,542/1,542 active strings translated
• zero empty or fuzzy entries
• msgid values and PO metadata unchanged
• gettext placeholders and HTML markup preserved
• msgfmt --check --check-format passed
• all translation catalogs compiled successfully with scripts/compile_translations.sh

Worked on by

• Meska