chore(deps): update dependency i18next to v26

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
i18next (source)	25.10.10 → 26.0.4

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Release Notes

i18next/i18next (i18next)

v26.0.4

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• fix(types): inline formatting options like {{price, currency(EUR)}} are now correctly resolved to their base format type (e.g. number for currency) instead of falling back to string 2378

v26.0.3

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• fix(types): addResourceBundle now accepts an optional 6th options parameter ({ silent?: boolean; skipCopy?: boolean }) matching the runtime API 2419

v26.0.2

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• fix(types): t("key", {} as TOptions) no longer produces a type error — the context constraint now bypasses strict checking when context is unknown (e.g. from TOptions) 2418

v26.0.1

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• fix: Formatter no longer crashes when alwaysFormat is true and no format specifier is present (format is undefined)
• fix: Formatter now returns undefined/null values as-is instead of producing NaN when the value is missing

v26.0.0

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This is a major breaking release:

Breaking Changes

• Remove deprecated initImmediate option — the backward-compatibility mapping from initImmediate to initAsync (introduced in v24) has been removed. Use initAsync instead.
• Remove legacy interpolation.format function — the old monolithic format function (interpolation: { format: (value, format, lng) => ... }) is no longer supported. The built-in Formatter (or a custom Formatter module via .use()) is now always used. Migrate to the new formatting approach using i18next.services.formatter.add() or .addCached() for custom formatters.
• Remove console support notice — the console support notice introduced in v25.8.0 has been removed, along with the showSupportNotice option and all related internal suppression logic (globalThis.__i18next_supportNoticeShown, I18NEXT_NO_SUPPORT_NOTICE env var). See our blog post for the full story.
• Remove simplifyPluralSuffix option — this option was unused by the core PluralResolver (which relies entirely on Intl.PluralRules). It only had an effect in the old v1/v2/v3 compatibility layer. The v4 test compatibility layer now defaults to true internally.
• Remove deprecated @babel/polyfill from devDependencies.

Improvements

• Code modernization across all source files:
  • Replace indexOf() > -1 / indexOf() < 0 with .includes() (~40+ occurrences)
  • Replace indexOf() === 0 with .startsWith() where appropriate
  • Replace var with const, '' + object with String(object), .substring() with .slice()
  • Replace .apply(observer, [event, ...args]) with direct call observer(event, ...args)
  • Remove unnecessary .call(this, ...) in BackendConnector retry logic
  • Fix array-callback-return in LanguageUtils getBestMatchFromCodes
  • Clean up all stale eslint-disable comments from source files
• EventEmitter: add once() method for one-time event subscriptions
• Memory leak fix: move module-level checkedLoadedFor cache to Translator instance, preventing cross-instance state leakage
• TypeScript: fix BackendModule generic parameter naming inconsistency between CJS and ESM type definitions
• TypeScript: add once() method to i18n and ResourceStore type interfaces
• ESLint 9: migrate from ESLint 8 (airbnb-base) to ESLint 9 flat config with neostandard
• Vitest 4: upgrade from vitest 3 to vitest 4, migrate workspace files to test.projects config

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[cypress]

frontend    Run #4661

Run Properties:   Passed #4661  •  cf3e758a21 ℹ️: Merge 299a723a771615f2b19a686b5b46bbfbaeed1646 into edb07ce6e321e4ff92357217377f...

Project	frontend
Branch Review	renovate/i18next-26.x
Run status	Passed #4661
Run duration	01m 39s
Commit	cf3e758a21 ℹ️: Merge 299a723a771615f2b19a686b5b46bbfbaeed1646 into edb07ce6e321e4ff92357217377f...
Committer	renovate[bot]
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Test results
Failures	0
Flaky	0
Pending	0
Skipped	0
Passing	36
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