[Zig] Implement FeeOracle module

[roninjin10]

Summary

Implement FeeOracle module in Zig for gas price estimation.

Required Features

Gas Price Estimation

• getGasPrice - Legacy gas price
• getMaxFeePerGas - EIP-1559 max fee
• getMaxPriorityFeePerGas - EIP-1559 priority fee
• estimateFees - Combined fee estimation

Fee History

• getFeeHistory - Historical fee data
• Percentile calculations
• Base fee prediction

Blob Fees (EIP-4844)

• getBlobBaseFee - Current blob base fee
• estimateBlobFees - Blob fee estimation

Strategies

• Fast/Standard/Slow presets
• Custom percentile support
• Network-specific defaults

Current State

Module missing entirely in Zig.

Note: Issue created by Claude AI assistant, not @roninjin10 or @fucory