Port route 4-c: NPC shop (PythonShop.cpp) + app cursor state

- UserInterface/PythonShop.cpp ported verbatim (shop module, initshop after initfly);
  pending stub and module stubs removed.
- 40250 PythonApplicationCursor.cpp and SetMouseHandler moved into the platform
  CPythonApplication on file-static members; GetCursorNum out of line, since uishop's
  app.GetCursor() dereferenced the missing application object.
- Fake server: general store (npclist 9003) answers CG_ON_CLICK with GC_SHOP START,
  CG_SHOP BUY/SELL2/END like CShop::Buy / CShopManager::Sell.
- port.login_flow step 10: click the shopkeeper, right-click buy, drag-sell, ESC close.

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

extension/src/platform/UserInterface/PythonApplication.cpp

@@ -301,15 +301,113 @@ void CPythonApplication::OnUIRender()
 	UI::CWindowManager& rkUIMgr=UI::CWindowManager::Instance();
 	rkUIMgr.Render();
 }
-BOOL CPythonApplication::SetCursorNum(int) { MT_PLATFORM_STUB(); return FALSE; }
-void CPythonApplication::SetCursorVisible(BOOL, bool) { MT_PLATFORM_STUB(); }
-BOOL CPythonApplication::GetCursorVisible() { MT_PLATFORM_STUB(); return FALSE; }
-bool CPythonApplication::GetLiarCursorOn() { MT_PLATFORM_STUB(); return false; }
-void CPythonApplication::SetCursorMode(int) { MT_PLATFORM_STUB(); }
-// 40250 returns m_iCursorMode, CURSOR_MODE_HARDWARE from the constructor until SetCursorMode (PythonApplicationCursor.cpp:92).
-// PORT: SetCursorMode is still a stub, so the mode stays the constructor's.
-int CPythonApplication::GetCursorMode() { return CURSOR_MODE_HARDWARE; }
-void CPythonApplication::SetMouseHandler(PyObject*) { MT_PLATFORM_STUB(); }
+// 40250 PythonApplicationCursor.cpp. PORT: the members live here until the application object exists
+// (initial values from the constructor and CreateCursors); the host draws no hardware cursor, so every
+// shape in [0, CURSOR_COUNT) counts as loaded in place of m_CursorHandleMap.
+namespace
+{
+int s_iCursorNum = CPythonApplication::CURSOR_SHAPE_NORMAL;           // m_iCursorNum
+int s_iContinuousCursorNum = CPythonApplication::CURSOR_SHAPE_NORMAL; // m_iContinuousCursorNum
+BOOL s_bCursorVisible = TRUE;                                         // m_bCursorVisible
+bool s_bLiarCursorOn = false;                                         // m_bLiarCursorOn
+int s_iCursorMode = CPythonApplication::CURSOR_MODE_HARDWARE;         // m_iCursorMode
+PyObject* s_poMouseHandler = NULL;                                    // m_poMouseHandler
+}
+
+void CPythonApplication::SetCursorVisible(BOOL bFlag, bool bLiarCursorOn)
+{
+	s_bCursorVisible = bFlag;
+	s_bLiarCursorOn = bLiarCursorOn;
+	// PORT: 40250 also counts ShowCursor up or down in hardware mode; the host has no OS cursor to hide.
+}
+
+BOOL CPythonApplication::GetCursorVisible()
+{
+	return s_bCursorVisible;
+}
+
+bool CPythonApplication::GetLiarCursorOn()
+{
+	return s_bLiarCursorOn;
+}
+
+int CPythonApplication::GetCursorMode()
+{
+	return s_iCursorMode;
+}
+
+int CPythonApplication::GetCursorNum()
+{
+	return s_iCursorNum;
+}
+
+BOOL CPythonApplication::__IsContinuousChangeTypeCursor(int iCursorNum)
+{
+	switch (iCursorNum)
+	{
+		case CURSOR_SHAPE_NORMAL:
+		case CURSOR_SHAPE_ATTACK:
+		case CURSOR_SHAPE_TARGET:
+		case CURSOR_SHAPE_MAGIC:
+		case CURSOR_SHAPE_BUY:
+		case CURSOR_SHAPE_SELL:
+			return TRUE;
+			break;
+	}
+
+	return FALSE;
+}
+
+BOOL CPythonApplication::SetCursorNum(int iCursorNum)
+{
+	if (CURSOR_SHAPE_NORMAL == iCursorNum)
+	{
+		if (!__IsContinuousChangeTypeCursor(s_iCursorNum))
+		{
+			iCursorNum = s_iContinuousCursorNum;
+		}
+	}
+	else
+	{
+		if (__IsContinuousChangeTypeCursor(s_iCursorNum))
+		{
+			s_iContinuousCursorNum = s_iCursorNum;
+		}
+	}
+
+	if (CURSOR_MODE_HARDWARE == s_iCursorMode)
+	{
+		// PORT: m_CursorHandleMap.find(iCursorNum) and SetCursor(hCursor).
+		if (iCursorNum < 0 || iCursorNum >= CURSOR_COUNT)
+			return FALSE;
+	}
+
+	s_iCursorNum = iCursorNum;
+
+	PyCallClassMemberFunc(s_poMouseHandler, "ChangeCursor", Py_BuildValue("(i)", s_iCursorNum));
+
+	return TRUE;
+}
+
+void CPythonApplication::SetCursorMode(int iMode)
+{
+	switch (iMode)
+	{
+		case CURSOR_MODE_HARDWARE:
+			s_iCursorMode = CURSOR_MODE_HARDWARE;
+			break;
+
+		case CURSOR_MODE_SOFTWARE:
+			s_iCursorMode = CURSOR_MODE_SOFTWARE;
+			break;
+	}
+}
+
+// 40250 PythonApplication.cpp:871.
+void CPythonApplication::SetMouseHandler(PyObject* poMouseHandler)
+{
+	s_poMouseHandler = poMouseHandler;
+}
 void CPythonApplication::SetGlobalCenterPosition(LONG, LONG) { MT_PLATFORM_STUB(); }
 void CPythonApplication::SetFPS(int) { MT_PLATFORM_STUB(); }
 time_t CPythonApplication::GetServerTime() { MT_PLATFORM_STUB(); return 0; }