Add WalletDb Initialization to MempoolNode::new() in src/mempool.rs

[Sophie-Ag00001]

PR Description: Add WalletDb Initialization to MempoolNode

Summary of Changes

This pull request introduces WalletDb initialization within the MempoolNode::new() function located in src/mempool.rs. The implementation mirrors the WalletDb setup found in src/miner.rs, creating an instance of WalletDb during the initialization of MempoolNode.

Motivation

The addition of WalletDb to MempoolNode is aimed at enhancing the functionality and consistency across components that depend on wallet operations. By ensuring that MempoolNode can access WalletDb, we improve its overall integration and enable future features that may require wallet interactions.

Background

The WalletDb component provides essential wallet functionalities that are already utilized in the miner context. To provide a similar level of access to the mempool, it's necessary to align MempoolNode with the existing architecture while adhering to the project's design principles.

Testing Instructions

To validate the implementation:

1. Ensure that the project builds successfully without any errors.
2. Initialize a MempoolNode instance and verify that the WalletDb is correctly instantiated.
3. Run existing unit tests to confirm no regressions have been introduced.
4. If applicable, create and run additional tests that check the interactions between MempoolNode and WalletDb.

Known Issues / Limitations

• Currently, there are no known issues related to this modification.
• Future enhancements may require a more complex wallet context setup that is not yet addressed in this implementation.

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Please review the changes and provide any feedback or suggestions. Thank you!