[Fix] DeepSeek V4 costs are underestimated after pricing changes

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

What changed

• Updates first-party DeepSeek V4 Pro and Flash cost estimates to the peak rates taking effect at 16:00 UTC on August 16, 2026; off-peak rates are half price.
• Keeps OpenCode Go's independently published discounted rates instead of applying first-party pricing to that subscription route.
• Adds separate Baseten and Fireworks entries for the V4 Pro 0813 checkpoint while retaining the preview-weight IDs and prices.
• Corrects Fireworks preview cached-input pricing and marks both first-party V4 models as text-only.
• Expands regression coverage across first-party, OpenCode Go, Baseten, and Fireworks IDs and prices.

Why this change was made

DeepSeek announced substantial peak/off-peak price increases after this PR was opened, and Baseten and Fireworks now expose the 0813 checkpoint separately from the earlier preview weights. The static estimator uses peak prices so it does not understate first-party costs, while provider-specific routes retain their own published prices.

Impact

Users get conservative first-party DeepSeek cost estimates and accurate route-specific metadata without conflating preview weights, the 0813 checkpoint, or OpenCode Go's discounted pricing.

Related PRs

• Documentation: [Docs] Document DeepSeek V4 pricing schedules Zoo-Code-Docs#27

Screenshots

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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Addressed in 498a89d: limited 0813 labeling to DeepSeek and OpenCode Go, restored Fireworks preview-weight metadata, kept Baseten undated, corrected V4 Pro image support and OpenCode Go pricing, removed the unverified Baseten cache-write price, and expanded regression coverage. The draft PR metadata and final proof now match the shipped distinction.