Get realized FX volatility for a currency pair.
Computes 30-day and 90-day annualized volatility from historical
ECB reference rates (standard deviation of daily log returns,
annualized by sqrt(252)). Returns a qualitative bucket:
LOW (<5%), MEDIUM (5-15%), HIGH (15-25%), VERY_HIGH (>25%),
PEGGED (currency peg — near-zero volatility, e.g., USD/AED, USD/HKD).
Also returns practical daily/weekly movement estimates and a
settlement_risk_note explaining what the volatility means over a
typical T+2 settlement period — use these to advise users on FX
risk for their specific payment.
Args:
base: Base currency (ISO 4217, e.g., "EUR")
target: Target currency (ISO 4217, e.g., "TRY")
Examples:
fx_volatility("EUR", "USD")
fx_volatility("USD", "TRY")