feat: add flexible nonce parameter support

- Add nonce_account and current_nonce to trade parameters
- Remove hardcoded NonceCache dependency from nonce_manager
- Update examples and documentation for new nonce usage
- Fix nonce documentation errors and improve clarity

examples/middleware_system/src/main.rs

@@ -99,6 +99,8 @@ async fn test_middleware() -> AnyResult<()> {
         close_wsol_ata: true,
         create_mint_ata: true,
         open_seed_optimize: false,
+        nonce_account: None,
+        current_nonce: None,
     };
     client.buy(buy_params).await?;
     println!("tip: This transaction will not succeed because we're using a test account. You can modify the code to initialize the payer with your own private key");