fix(ffi): use .cast() instead of as cast for raw pointer conversion

Replace 'as *mut u8' casts with .cast::<u8>() method to fix clippy
warnings about unnecessary casts on ARM architectures.

On ARM, c_char is u8, making the explicit cast unnecessary. Using
.cast::<u8>() is the modern Rust approach and avoids clippy warnings
while maintaining platform compatibility.

Author: PastaPastaPasta

key-wallet-ffi/src/derivation.rs

@@ -131,7 +131,7 @@ pub extern "C" fn derivation_bip44_account_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);
@@ -189,7 +189,7 @@ pub extern "C" fn derivation_bip44_payment_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);
@@ -244,7 +244,7 @@ pub extern "C" fn derivation_coinjoin_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);
@@ -299,7 +299,7 @@ pub extern "C" fn derivation_identity_registration_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);
@@ -356,7 +356,7 @@ pub extern "C" fn derivation_identity_topup_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);
@@ -417,7 +417,7 @@ pub extern "C" fn derivation_identity_authentication_path(
     }
 
     unsafe {
-        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out as *mut u8, bytes.len());
+        ptr::copy_nonoverlapping(bytes.as_ptr(), path_out.cast::<u8>(), bytes.len());
     }
 
     FFIError::set_success(error);