Add vault protocol

This skill guides you through adding support for a new ERC-4626 vault protocol to the eth_defi library.

Required inputs

Before starting, gather the following information from the user:

1. Vault smart contract address - The address of an example vault contract on a blockchain
2. Protocol name - Human-readable name (e.g., "Plutus", "IPOR", "Morpho")
3. Protocol slug - Snake_case identifier for code (e.g., "plutus", "ipor", "morpho")
4. Chain - Which blockchain (Ethereum, Arbitrum, Base, etc.)
5. Block explorer URL - To fetch the ABI (e.g., Etherscan, Arbiscan, Basescan)
6. Single vault protocol: Some protocols, especially ones issuing out their own stablecoin, are know to have only a single vault for the stablecoin staking. Example protocols are like like Spark, Ethena, Cap. In this case use HARDCODED_PROTOCOLS classification later, as there is no point to create complex vault smart contract detection patterns if the protocol does not need it.
7. Risk level: Optional. If not given, set to None

Step-by-step implementation

Step 1: Download and store the ABI