Make the global HTMLAttributes children type augmentation opt-in (next major)

Context

index.d.ts:174-187 ships a declare module 'react' global augmentation that overrides HTMLAttributes<T>.children (plus JSX.IntrinsicAttributes.i18nIsDynamicList) for every consumer of react-i18next, whether or not they use the feature it exists for.

The children override is defanged by default (ReactI18NextChildren resolves the object case to never unless CustomTypeOptions.allowObjectInHTMLChildren is true), but it still patches React's global types and remains the one coupling point to React's internal type shape. It has clashed before (#1681, "HTMLAttributes is not assignable to DOMAttributes", Sep 2023) and every React major forces a re-check of this block (see the React 18 wave: #1476, #1483, #1543).

Proposal (next major)

Move the augmentation into an opt-in ambient module, e.g.:

// only needed when CustomTypeOptions.allowObjectInHTMLChildren is true
import 'react-i18next/augment-react';

Default installs then never touch React's global types.

Breaking-change note

Users who currently set allowObjectInHTMLChildren: true must add the one-line import; needs a prominent migration-guide entry.

Related mitigation already in place

The weekly types-compat workflow (.github/workflows/types-compat.yml, since 17.0.10) typechecks against the newest @types/react (pre-release tags when available), so breakage from upstream type changes is caught early either way.