feat: implement SwapEncoder for Hashflow

src/encoding/evm/approvals/permit2.rs

@@ -31,10 +31,6 @@ pub struct Permit2 {
     address: Address,
     client: EVMProvider,
     runtime_handle: Handle,
-    // Store the runtime to prevent it from being dropped before use.
-    // This is required since tycho-execution does not have a pre-existing runtime.
-    // However, if the library is used in a context where a runtime already exists, it is not
-    // necessary to store it.
     #[allow(dead_code)]
     runtime: Option<Arc<Runtime>>,
 }