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>

audit/port-map/EterBase/Poly/Base.cpp.json

@@ -0,0 +1,38 @@
+{
+  "reference": "EterBase/Poly/Base.cpp",
+  "reference_sha256": "44777e6173df4d43f20730d2a241ecb5a2576561cb5c49d89645ab83f119aa6d",
+  "priority": "P4",
+  "contracts": [],
+  "functions": {
+    "CBase::CBase": {
+      "status": "PORTED",
+      "impl": [
+        "extension/src/port/EterBase/Poly/Base.cpp:CBase::CBase"
+      ]
+    },
+    "CBase::~CBase": {
+      "status": "PORTED",
+      "impl": [
+        "extension/src/port/EterBase/Poly/Base.cpp:CBase::~CBase"
+      ]
+    },
+    "CBase::isNumber": {
+      "status": "PORTED",
+      "impl": [
+        "extension/src/port/EterBase/Poly/Base.cpp:CBase::isNumber"
+      ]
+    },
+    "CBase::isVar": {
+      "status": "PORTED",
+      "impl": [
+        "extension/src/port/EterBase/Poly/Base.cpp:CBase::isVar"
+      ]
+    },
+    "CBase::isSymbol": {
+      "status": "PORTED",
+      "impl": [
+        "extension/src/port/EterBase/Poly/Base.cpp:CBase::isSymbol"
+      ]
+    }
+  }
+}