wstrBTC ERC-4626 Wrapper

wstrBTC is an ERC-4626-compliant wrapper for strBTC, designed to ensure compatibility with DeFi protocols that require non-rebasing, fixed-balance tokens. While strBTC leverages a rebasing mechanism to reflect yield directly in user balances, many DeFi platforms are not optimized to support rebasing assets. wstrBTC solves this by wrapping strBTC into a standard vault interface, allowing users to deposit strBTC and receive a fixed-amount wstrBTC token in return. This enables seamless participation in DeFi applications such as lending markets, yield aggregators, and collateralized protocols. Internally, wstrBTC accrues yield through changes in its exchange rate relative to strBTC, preserving the underlying yield dynamics while maximizing composability and protocol compatibility.