chore: ai assistant to em

[astandrik]

• Ask in chats
• Create ticket https://nda.ya.ru/t/g47ciKHf7HDiTb
• Try Qwen
• Try openai-oss
• Reach cloud llm from preprod
• Reach em mcp from preprod
• .... ?

1. added service account with role ai.languageModels.user
2. use api-key + folder-id and OpenAI lib