port: CPythonSkill + skill module + EterBase/Poly (1:1 40250)

Copy PythonSkill.cpp and the EterBase/Poly formula parser verbatim, drop the
pending stand-in and the skill module stub, register initskill() after
initfly() and build CPythonSkill in m_pySkill's place. LoadLocaleData now
loads skilldesc/skilltable. Skill and item icon handles go through
Py_BuildPointer/PyTuple_GetPointer (ILP32 ints truncate 64-bit pointers).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

extension/src/port/EterBase/Poly/Base.h

@@ -0,0 +1,25 @@
+#ifndef __POLY_BASE_H__
+#define __POLY_BASE_H__
+
+#define MID_UNKNOWN		0
+#define MID_NUMBER		256
+#define MID_VARIABLE		512
+#define MID_SYMBOL		1024
+
+#define MID_LONG		MID_NUMBER + 1
+#define MID_SQRT		MID_NUMBER + 2
+#define MID_FRACTION		MID_NUMBER + 3
+
+class CBase  
+{
+    public:
+	bool isSymbol();
+	bool isVar();
+	bool isNumber();
+	int id;
+	CBase();
+	virtual ~CBase();
+
+};
+
+#endif