MPDX-9947 - Enforce useTranslation and disable use of i18n singleton

[zweatshirt]

Description

Jira ticket: https://jira.cru.org/browse/MPDX-9947

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Issue:

i18n.t() at module scope evaluates to a string at import time, before React renders and before translations have loaded. Since module bodies don't re-execute, those strings are frozen in English for the life of the page.

Two things in our setup make this unavoidable:

• src/lib/i18n.ts uses i18next-http-backend, so translation.json is fetched over the network. .init() is called synchronously but not awaited.
• UserPreferenceProvider calls i18n.changeLanguage() in a useEffect, after the GetUser query resolves

Fix: Why useTranslation instead of i18n.t

useTranslation() does two things, and the fix needs both:

1. t is called inside the component body, so the expression re-evaluates on every render instead of once.
2. The hook subscribes the component to languageChanged (react-i18next's bindI18n default) and
   calls setT with a fresh function, which guarantees that re-render actually happens when
   UserPreferenceProvider applies the saved language.

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Important files to review in this PR

• .eslintrc.js
• src/components/User/Preferences/UserPreferenceProvider.tsx
• src/components/Layouts/Primary/TopBar/Items/AddMenu/Items/AddDonation/AddDonation.tsx
• src/components/HrTools/AdditionalSalaryRequest/Shared/Helper/getHeader.ts
• src/components/Reports/Shared/SettingsDialog/SettingsDialog.tsx
• src/components/Tool/Appeal/InitialPage/AddAppealForm/AddAppealForm.tsx
• src/components/Tool/Home/ToolsListHome.ts
• src/components/Contacts/ContactDetails/ContactDetailsTab/Other/ContactDetailsOther.tsx
• tests/eslintrules/restrictedSyntaxHarness.ts
• src/components/Tool/FixCommitmentInfo/InputOptions/Frequencies.ts

Testing

Go to Settings → Preferences → Language → Deutsch, save, then open /accountLists/id/tools.
- On old code the tool names and descriptions stay English while the surrounding page chrome translates.
- In the preview environment with new code, the tool names and descriptions will change to the correct language.

Checklist:

• I have given my PR a title with the format "MPDX-(JIRA#) (summary sentence max 80 chars)"
• I have applied the appropriate labels (Add the label "Preview" to automatically create a preview environment)
• I have run the Claude Code /quality:agent-review command locally and fixed any relevant suggestions
• I have requested a review from another person on the project
• I have tested my changes in preview or in staging
• I have cleaned up my commit history

[github-actions]

Bundle sizes [mpdx-react]

Compared against 5f0edc3

No significant changes found

[github-actions]

Preview branch generated at https://enforce-usetranslation.d3dytjb8adxkk5.amplifyapp.com

[zweatshirt]

@dr-bizz Thanks for considering this. The core code is a lot less than the change implies. I listed the files that are important to look at.

I did an agent review locally, it is mostly happy with the results, but this deserves a human look. Thanks Daniel!