ACCEPTANCE CRITERIA (9/9)

☑ 1. Script `scripts/correlation-check.js` reads all timeseries files (bcb-indicators.json, commodities.json, fred-indicators.json)

☑ 2. Implements Pearson correlation coefficient calculation without external dependencies

☑ 3. Requires minimum 12 data points per pair -- below that, reports "dados insuficientes" without error

☑ 4. Analyzes 5 predefined indicator pairs: (petroleo_wti, usd_brl), (selic, usd_brl), (petroleo_brent, ipca), (usd_brl, ipca), (fed_funds_rate, usd_brl)

☑ 5. For each pair, tests correlation at lags: 0, 1, 2, 4, 8, 12 weeks. Reports the lag with highest |r|

☑ 6. Classifies correlation strength: strong (|r| > 0.7), moderate (0.4-0.7), weak (< 0.4)

☑ 7. Output `data/state/correlation-history.json` with calculated_at, data_points_available, correlations array, insufficient_data array

☑ 8. Supports `--dry-run`, `--verbose`, `--help`, `--lag {weeks}` flags

☑ 9. No API key or external data needed -- works entirely on local timeseries files