Description

This PR implements the DeepSeek provider for the LLM Proxy and Chat, resolving issue #1846.

Changes

• Added deepseek to SupportedProviders.
• Added configuration for ARCHESTRA_DEEPSEEK_BASE_URL and API key.
• Implemented DeepSeekAdapter (using OpenAI compatibility layer).
• Added proxy routes for DeepSeek.
• Updated frontend API key form to include DeepSeek.

Checklist

• Provider registered in constants
• Config updated
• Adapter implemented
• Routes added
• Frontend updated

Note: Please add the deepseek.png icon to platform/frontend/public/icons/ manually as binary files cannot be added via this PR flow. /claim #1846