[feature]: Add Hindi (hi) locale support to i18n system

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Summary

Plane currently does not support Hindi (hi) as a language option in its i18n system.

This feature proposes adding Hindi locale support, including translations for core UI components, accessibility labels, and empty states. The implementation follows the existing i18n structure and aligns with the latest schema used in the English locale.

A complete implementation has already been developed and submitted in PR #8897.

Why should this be worked on?

Adding Hindi language support improves accessibility for a large user base, as Hindi is one of the most widely spoken languages globally.

This enhancement aligns with Plane’s goal of being accessible and usable across diverse regions. It also strengthens internationalization efforts by expanding language coverage.

Since the implementation is already completed and aligned with the existing schema, this can be integrated with minimal additional effort while providing significant user value.