Add console.warn when calculateMessageCost encounters an unknown model,
so pricing.json gaps are visible rather than silently returning $0.
Update tests to expect the warning.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Create a unified pricing module in src/shared/utils/ that wraps
resources/pricing.json with typed lookup, tiered cost calculation,
and display pricing helpers. This is the foundation for consolidating
the dual cost calculation systems (main jsonl.ts + renderer sessionAnalyzer).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>