feat: Add Raydium AMM V4 support and middleware system

- Add Raydium AMM V4 trading protocol support
- Implement instruction middleware system for dynamic processing
- Refactor trade executors to support middleware parameters
- Add fee calculation and slippage protection mechanisms
- Maintain backward compatibility with optional middleware

src/trading/middleware/mod.rs

@@ -0,0 +1,4 @@
+pub mod traits;
+pub mod builtin;
+
+pub use traits::{InstructionMiddleware, MiddlewareManager};