fix(i18n): respect stored user locale over browser language

[iMeet07]

Description

This PR fixes an issue where the application always reset the locale to the browser language on refresh, ignoring the user's previously selected language stored in preferences.

Changes:

• Normalized stored language codes (it → it-IT, en → en-US)
• Updated layout logic to prioritize stored user preference over window.navigator.language
• Ensured correct fallback behavior

Now the selected language persists correctly after refresh.

Fixes unexpected locale override on reload.

---

Checklist:

Author Self-Review:

• I have performed a self-review of my own code.
• I understand the changes I'm proposing and why they are needed.
• My changes generate no new warnings or errors (linting, console).

LLM Usage Disclosure:

• I used AI assistance for debugging and reasoning but reviewed and validated the changes manually.

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Project	Deployment	Actions	Updated (UTC)
explorer	Ready	Preview, Comment	Feb 21, 2026 6:39pm

[VaiTon]

I can't reproduce the original issue. Beside this, why are it-IT and en-US hardcoded?

[VaiTon]

We already do this in getBrowserLocale, which is called in getLocale. What does this fix?

[iMeet07]

Thanks for the feedback.
The issue I observed was that when preferences.lang stored a short code like "it", it didn’t match the registered locales ("it-IT"), causing fallback to "en-US" on refresh.
Instead of handling this in +layout.ts, I will move the normalization into getBrowserLocale() to avoid duplication and keep locale resolution centralized.

[VaiTon]

Thank you! Let me know when the PR is ready :)