Added cleaned up structs and classes to proper header files.

source/engine/sys/sys_signin.h

@@ -0,0 +1,14 @@
+#pragma once
+
+// Reconstructed C++ declarations from IDA Local Types and PDB/DIA metadata.
+// Original PDB header: w:\tech5\engine\sys\sys_signin.h
+// Recovered logical types: 1
+// Signatures retain Xbox 360 ABI evidence and may still require manual review.
+
+
+// IDA Local Type ordinal 12255; PDB kind: class.
+class idSysSignal
+{
+public:
+  void *handle;
+};