Summary

Remove legacy token-only pricing helpers that are no longer used by production cost accounting.

Evidence

• crates/tui/src/pricing.rs:246 calculate_turn_cost, :256 calculate_turn_cost_estimate, and :271 calculate_turn_cost_with_pricing are only used by pricing tests.
• Production cost accounting uses calculate_turn_cost_from_usage, calculate_turn_cost_estimate_from_usage, and token_usage_for_pricing to honor cache-hit/cache-miss fields.
• crates/tui/src/pricing.rs:363 format_cost has no callers; production uses currency-aware formatters.

Suggested Change

Delete token-only/USD-only legacy helpers and update or remove tests that only preserve the legacy API. Keep usage-aware cost helpers and currency-aware display helpers.

Risk & Confidence

Confidence: high. Risk: low-medium; pricing is user-visible, so tests should cover the usage-aware path after deletion.

Verification Checklist

• Run cargo test -p codewhale-tui pricing cost_status scorecard -- --nocapture.
• Run cargo check -p codewhale-tui --all-targets.
• Confirm rg "calculate_turn_cost\(|calculate_turn_cost_estimate\(|format_cost\(" crates/tui/src crates/tui/tests only finds active intended APIs.