Function n3_prepare_migration 

fn n3_prepare_migration(
    frame: &mut MigrationFrame,
    msg_buf: *mut u8,
    sender_cr3: u64,
    sender_rsp: u64,
    sender_rip: u64,
    handler_stack_top: u64,
    receiver_task: &Task,
    msg: &[u8],
) -> Result<(), IpcError>

Prepare a MigrationFrame for a send operation.

Sets up src_ctx (sender), dst_ctx (receiver), copies the message into the shared buffer, increments generation, and transitions state to Active.