fix(docs): critical translation errors in Russian zen page

[JustStepan]

Description

The Russian translation of packages/web/src/content/docs/ru/zen.mdx contains multiple errors that break readability and understanding.

Critical issues (break understanding):

1. Line 13: "Открытый код" appears instead of "OpenCode" (product name should not be translated)
2. Line 19: Incomplete sentence: "но лишь некоторые из них." (missing verb/continuation)
3. Line 73: Broken text: "добавляете свой платежный аккаунт. подробности и скопируйте" (random period mid-sentence)
4. Line 28: Unclear: "что они обслуживаются. правильно." (meaning lost)
5. Line 188: Grammar error: "Мы будем скоро поделимся" (incorrect verb conjugation)

Serious translation issues:

• "агентов кодирования" → should be "кодинг-агентов" (coding agents)
• "Принесите свой ключ" → awkward literal translation, should be "Использование собственных API-ключей"
• "автоматическая перезагрузка" → confusing (means "reboot"), should be "автопополнение баланса"
• "курировать модели" → wrong word choice, should be "выбирать модели"
• Inconsistent terminology: "провайдеров/поставщиков" mixed throughout

I can fix all of these (and other minor errors) in a single PR that improves overall translation quality.

Plugins

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OpenCode version

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Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

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