[FEATURE] Localization (i18n)

Problem

There's currently no support for localization in OpenCut. This makes it difficult for non-English speakers to use the application effectively.
I remember how the Russian community waited for official localization in CapCut, and how some enthusiasts had to create their own mods.
Let's not repeat history - OpenCut should be accessible to everyone from the start.

Solution

Implement an internationalization (i18n) system. A good option would be something like react-intl or any other well-maintained i18n library for Next.js.

Alternative

Hardcoded translations in components
Community-maintained forks with localized versions

Anything else?

I have previous experience doing translations - not for Next.js, but for React-based browser extensions like Tabliss and its forks.
I'd be happy to contribute my knowledge and help get the Russian localization off the ground here as well!

The issue names no files, tests, or entry points. Start by reviewing the existing Next.js and React structure, then evaluate react-intl or another maintained i18n library. Done means the application supports a defined localization system and an initial Russian translation can be added.