Add ENS utility library for mainnet address resolution

[devin-ai-integration]

Add ENS utility library for mainnet address resolution

Summary

This PR introduces a standalone ENS (Ethereum Name Service) utility library for resolving ENS names to Ethereum addresses on mainnet. The implementation follows the established patterns from the existing ArbiScan utilities and includes:

• ENSClient class for performing ENS operations with configurable RPC providers
• Pydantic models (ENSResolution, ReverseENSResolution) for structured data handling
• Utility functions for both forward (name → address) and reverse (address → name) resolution
• Input validation using the existing sanitize_user_input pattern
• web3.py dependency added for onchain ENS lookups

The library supports custom RPC providers via environment variables (INFURA_PROJECT_ID) with fallback to public endpoints.

Review & Testing Checklist for Human

• Test ENS resolution with various real ENS names (vitalik.eth, ens.eth, etc.) to verify functionality
• Verify error handling with invalid inputs (non-.eth names, malformed addresses, non-existent names)
• Test network failure scenarios by temporarily blocking network access or using invalid provider URLs
• Check reverse resolution works correctly for addresses that do/don't have ENS names
• Verify web3 dependency doesn't conflict with existing code and installs correctly in clean environment

Recommended test plan: Run the included test_ens_utility.py script and verify it handles both successful resolutions and graceful error handling for network issues.

---

Diagram

%%{ init : { "theme" : "default" }}%%
flowchart TD
    pyproject["pyproject.toml<br/>+web3 dependency"]:::minor-edit
    
    ens_models["src/talos/models/ens.py<br/>ENSResolution models"]:::major-edit
    ens_utils["src/talos/utils/ens.py<br/>ENSClient + utilities"]:::major-edit
    
    arbiscan_utils["src/talos/utils/arbiscan.py<br/>ArbiScanClient pattern"]:::context
    arbiscan_models["src/talos/models/arbiscan.py<br/>Pydantic models pattern"]:::context
    validation["src/talos/utils/validation.py<br/>sanitize_user_input"]:::context
    
    ens_utils --> ens_models
    ens_utils --> validation
    ens_models -.-> arbiscan_models
    ens_utils -.-> arbiscan_utils
    pyproject --> ens_utils
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit  
        L3[Context/No Edit]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB  
    classDef context fill:#F5F5F5

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Notes

• Network dependency risk: The utility relies on external RPC providers which could be rate-limited or fail. Consider implementing retry logic and better fallback mechanisms for production use.
• Type safety: Had to use type: ignore[union-attr] comments for web3.py's complex union types - this is a known limitation of web3.py's type annotations.
• Testing limitations: Only basic manual testing was performed. Consider adding comprehensive unit tests with mocked network calls for better reliability.

Session details: Requested by @talos-agent
Link to Devin run: https://app.devin.ai/sessions/ade086eff99240beb646051dfe16da92

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