feat: add database and state management modules

[qj0r9j0vc2]

Changes

This PR implements the foundational database abstraction and state management for the execution layer.

Database Module (database.rs)

• Provider trait for storage backend abstraction
• InMemoryProvider for testing and development
• CipherBftDatabase implementing revm::Database trait
• LRU caching for accounts and bytecode
• Support for pending changes and batch operations

State Module (state.rs)

• StateManager for state root computation
• Periodic state root computation (every 100 blocks)
• Snapshot management for rollback capability
• Automatic snapshot pruning
• State root caching with LRU

Dependencies

• Uses revm 19 + alloy 0.8 for compatibility
• Adds lru and dashmap for caching and concurrent access