chore(fe): update Italian translations

[sea-snake-translation-bot]

New translations were missing for `it`. This PR adds the missing translations.

Changes

• Translated missing entries in `src/frontend/src/lib/locales/it.po`

[sea-snake-translation-bot]

@AntonioVentilii this PR may already be merged by the time you see it, but if you spot any translation mistakes feel free to leave comments or suggestions here — they'll be picked up by AI in a future run. Besides specific fixes, broader feedback is also welcome (e.g., tone, terminology preferences, style guidelines) — these will be reviewed and applied across all future translations.

[Copilot]

Pull request overview

Updates the Italian Lingui catalog to cover newly introduced SSO error/status messages in the frontend (notably SignInWithSso.svelte), ensuring the it locale no longer falls back to English for those strings.

Changes:

• Added Italian translations for new SSO timeout and “load SSO settings” network error messages.
• Removed two obsolete Italian entries that no longer appear to be referenced in the frontend source.

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[sea-snake-translation-bot]

Thanks for the review summary, @copilot-pull-request-reviewer! The overview looks accurate — no code changes needed based on this.