Refactor: Project File Structure Organization

[alexanderwiederin]

Refactor: Project File Structure Organization

Add standardized file structure and organization to improve project maintainability and navigation.

Current State

The project currently lacks a clear file structure, which makes it hard to read and contribute to.

Proposed Structure (preliminary)

src/
├── lib.rs                    # c_serialize, KernelError
├── ffi/                      # Foreign Function Interface / C bindings
│   ├── mod.rs
│   ├── c_helpers.rs          # Utilities for C callback patterns (incl. cast_string)
│   └── constants.rs          # C-side constants
├── core/                     # Core Bitcoin data types and consensus logic
│   ├── mod.rs
│   ├── block.rs              # Block, BlockHash, BlockSpentOutputs, TransactionSpentOutputs
│   ├── transaction.rs        # Transaction, TxOut, Coin
│   ├── script.rs             # ScriptPubkey
│   └── verify.rs             # Script verification logic, flags, ScriptVerifyStatus ScriptVerifyError
├── state/                    # Chainstate & contextual info
│   ├── mod.rs
│   ├── chainstate.rs         # ChainstateManager
│   ├── context.rs            # Context, ContextBuilder, ChainType
│   └── chain.rs              # Chain, ChainIterator
├── notifications/            # Callback interfaces for notifications
│   ├── mod.rs
│   ├── kernel.rs             # KernelNotificationInterface callbacks
│   ├── validation.rs         # ValidationInterface callbacks
│   └── types.rs              # SynchronizationState, ValidationMode, BlockValidationResult, Warning
└── log/
   ├── mod.rs
   └── logging.rs            # Logger, LogLevel, LogCategory and logging helpers (e.g. disable_logging)

Implementation Considerations

• Try to maintain backward compatibility during any restructuring