Implement remaining eth_ namespaced RPC endpoints

[LeoPatOZ]

Summary

Not all eth_ namespaced RPC methods are currently exposed through the Robust Provider wrapper.

Problem

Users who need to call less common eth_ methods must bypass the Robust Provider and lose the retry/fallback functionality.

Proposed Solution

• Audit the full list of eth_ methods from the Ethereum JSON-RPC spec
• Identify which methods are missing from our implementation
• Add wrappers for each missing method (typically 2-3 lines per method)
• Add corresponding tests