feat(firebase_ui_localizations): translate untranslated lable for Tha…

[nattapong2041]

Description

Translate non-translate label for Thai

Related Issues

Not complete translation of Thai in the FirebaseUI

Checklist

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• All existing and new tests are passing.
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Breaking Change

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[Copilot]

Pull Request Overview

This PR completes the Thai localization for Firebase UI by translating 32 previously untranslated English strings to Thai. The changes ensure that Thai-speaking users have a fully localized experience across email verification, file upload, account management, and provider linking features.

Key Changes:

• Translated all remaining English strings in Thai localization to proper Thai text
• Updated timestamp metadata to reflect the latest modification
• Maintained consistency between .dart and .arb localization files

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/firebase_ui_localizations/lib/src/lang/th.dart	Updated Thai localization class with 32 translated strings for email verification, file upload, account deletion, and provider management features
packages/firebase_ui_localizations/lib/l10n/firebase_ui_th.arb	Synchronized ARB localization file with corresponding Thai translations and updated timestamp metadata

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