Restore estimated costs for Azure GPT-6 reviews

[Vilin97]

Azure-backed reviews currently show tokens and Codex quota billing but omit a dollar cost. Restore an Estimated cost in both single-review and multi-rubric comments using official GPT-6-Astra Standard API pricing: $10/M input and $50/M output, or $20/M and $75/M above 272K input tokens per request. For example, 100K input plus 10K output now displays Estimated cost: $1.5000.

The footer identifies this as a Standard API equivalent using uncached input rates, alongside the existing Codex quota billing note. Each rubric is priced before summing, and incomplete usage is marked partial instead of implying a zero cost. Azure routing and authentication stay in place.

Validation: all 338 Python tests pass, including pricing boundaries, five-rubric aggregation, and unavailable usage; Ruff lint and format checks pass.

[greptile-apps]

Advisory cross-file review against Lean Pool's supervisory rubric. This is not by itself a significance, source-verification, or merge verdict.

The PR appears safe to merge; no actionable correctness, security, or repository-rule issues remain.

Summary

• Adds GPT-6-Astra Standard API rates and the model-specific 272K-token boundary behavior.
• Prices multi-rubric reviews per request before aggregation and marks incomplete totals appropriately.
• Documents that estimates use uncached Standard API input rates and are not actual Codex invoices.
• Adds tests for pricing boundaries, aggregation, unavailable usage, and partial estimates.

_{Reviews (1) · Last reviewed commit: "Restore estimated dollar costs for Azure..."}

[github-actions]

LLM review skipped: PR touches no .lean files. Push a Lean change or comment /review after one lands to re-trigger.