feat(rln): implement wallet authentication & connection

[danisharora099]

Description

To enable users to interact with RLNv2 smart contracts, they need to connect their Web3 wallets (MetaMask, WalletConnect, etc.). This issue involves integrating wallet authentication into the frontend.

User Story

• As a user, I want to connect my Web3 wallet to the RLNv2 Web Dapp, so that I can manage my RLN membership securely.

Proposed Solution / Feature Design

• Implement wallet connection via ethers.js or viem.
• Display the connected account and network details.
• Handle authentication state persistence and reconnections.
• Implement error handling for network mismatches and connection failures.

Optional: Diagram or Draft of Design

Notes

• Ensure compatibility with Sepolia
• Resolved by feat(keystore_management): new app, setup wallet connection/management with sepolia lab.waku.org#114