Mezo USDMUSD#645

MUSD is Mezo's Bitcoin-backed stablecoin, minted when users deposit BTC as collateral and borrow against it at low, fixed rates. The system uses a collateralized debt position (CDP) model, where each MUSD is fully backed by Bitcoin and can be redeemed for BTC, helping MUSD maintain its 1:1 peg to USD. Borrowers can access high loan-to-value ratios (up to ~90%) while the system maintains over-collateralization (system >110%, typical user >150%). Positions below minimum collateral ratio are automatically liquidated to keep all MUSD fully backed.