Write a Solidity Contract for a Multi-Signature Wallet

### 🧾 Project Description:
Build a basic multi-signature wallet smart contract in Solidity.

### ✨ Features:
- Owners can be added/removed
- Transactions require N-of-M approval
- Emits events for proposed/executed txs

### 📂 Suggested File:
`solidity/multisig-wallet.sol`

Great for contributors with some Solidity experience! 👨‍💻👩‍💻

Start with the requirements in the issue and inspect solidity/multisig-wallet.sol, if present. Define the owner-management and N-of-M approval behavior, transaction proposal/execution events, and the criteria for a complete contract before implementing. Confirm that all listed features work and that the contract is covered by the project's available checks.

Written by the indexing model from the issue text.