### What problem does this PR solve?
- Add complete Italian translation file with all UI sections
- Register Italian in LanguageAbbreviation enum and language maps
- Configure Italian translation in i18n config
- Add Italiano to language selector dropdown
### Type of change
- [x] Other (please describe):
## What
Added complete Italian language translation support to RAGFlow
## Changes
- Added comprehensive Italian translation file
([it.ts](ragflow/web/src/locales/it.ts:0:0-0:0)) with all UI sections
(1239 lines)
- Registered Italian in `LanguageAbbreviation` enum and all language
maps
- Configured Italian translation in i18n configuration
- Added "Italiano" to language selector dropdown
## Impact
- Italian users can now use RAGFlow in their native language
- All major UI components are translated including:
- Login/registration screens
- Knowledge base management
- Chat interface
- Settings and configuration
- Admin console
- Error messages and notifications
## Testing
- Verified all translation keys are present
- Confirmed language selector shows "Italiano" correctly
- Tested that no translation keys are missing
- All UI sections properly translated
Co-authored-by: PentaFrame <info@pentaframe.it>
