Fetch current gas prices for an EVM chain from the b3 gas oracle. Returns legacy tiers (low / standard / fast / instant) and, when available, EIP-1559 base fee + priority/max-fee tiers and historical analysis (level, percentile, vs1h/vs4h/vs24h ratios). Values are in gwei. Ideal for: gas-gated batching, cost-aware send timing, gas dashboards.
