[Docs] Explain DeepSeek V4 Pro provider versions

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​Opened on behalf of @taltas. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• Explains that DeepSeek and OpenCode Go route the stable deepseek-v4-pro alias to the first-party 0813 checkpoint.
• Identifies Fireworks AI and Baseten as serving the published V4 Pro preview weights through their own inference infrastructure.
• Lists each provider's exact model ID and version served in one table.
• Notes DeepSeek's warning that it plans a significant overall price increase, so hardcoded rates may need follow-up.

Why this change was made

The 0813 update changed the checkpoint behind DeepSeek's existing API alias rather than introducing a new model ID or new open weights. The provider guide needs to preserve that distinction so users do not assume every V4 Pro host serves the same checkpoint.

Impact

Users can choose a DeepSeek V4 Pro route with accurate expectations about the checkpoint, provider ID, and pricing stability.

Related PRs

• Extension: [Improve] Align DeepSeek V4 Pro provider metadata Zoo-Code#1237

Screenshots

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Addressed in ab2d4f4 and 1aead6b: the guide now distinguishes first-party 0813 routes from self-hosted preview weights, lists exact provider IDs/versions, and warns about DeepSeek's planned significant price increase. The draft PR metadata and screenshots were refreshed to the final rendered state.