[FEATURE]: Add Bengali (বাংলা) language support for the UI #34593

Feature hasn't been suggested before.

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Describe the enhancement you want to request

I'd like to request support for the Bengali (বাংলা) language in OpenCode's user interface.

Bengali is one of the most widely spoken languages in the world, with over 250 million speakers. Providing Bengali localization would make OpenCode more accessible to developers who are more comfortable using software in their native language.

I noticed that the repository already includes a Bengali translation of the README, but the application itself does not currently support Bengali UI localization.

Proposed Solution
Add Bengali (bn) as a supported locale.
Externalize all user-facing strings for translation (if not already done).
Allow users to select Bengali through the language settings or automatically detect the system locale.
Translate the following UI elements:
Menus
Commands
Settings
Dialogs
Error messages
Status messages
Help text
Benefits
Improves accessibility for millions of Bengali-speaking developers.
Encourages wider adoption in Bangladesh and West Bengal.
Makes OpenCode more inclusive for the global open-source community.
Contribution

I'd be happy to contribute the Bengali translations if this feature is accepted. I can also help review future translation updates to keep the localization accurate and consistent.