Task 385: AI Costs Report Visualizations

Status: DONE

Summary

ai-costs.md has only 1 bar chart despite 7-8 quantitative sections. Add:

1. Token distribution bar chart (cache reads 97.3% dominance)
2. Model usage breakdown bar chart (Haiku launches vs Sonnet vs Opus, with cost attribution)

Rationale

• CLAUDE.md: "Diagrams and graphs for clarity" — more figures are better than fewer
• ai-costs.md has the most significant visualization gap among all summary reports
• Token distribution and model usage are key findings buried in tables