fix: add gpt-5.4 codex pricing

[cuidong233]

Summary

• add Codex pricing entries for gpt-5.4 and gpt-5.4-codex
• make Codex cost calculations work for current GPT-5.4 usage logs
• add regression coverage for GPT-5.4 normalization and cost calculation

Why

CodexBar was already parsing and summing GPT-5.4 token usage, but the pricing table did not include GPT-5.4. That made large GPT-5.4 token totals appear alongside implausibly small USD totals.

Testing

• swift test --filter CostUsagePricingTests

Before / After

Before

After

Closes #602

[iam-brain]

5.4-codex doesn't exist, and 5.4 and 5.4-mini were already added before this was opened: CostUsagePricing.swift#L95)

Edit: your fork is 293 commits behind the current main. Update your app or rebase your fork to rebuild with the updates you're missing