feat: add candidate FreeCAD naming SDK and attachment oracles

Build and verify the candidate-only FreeCAD naming bridge and OCCT worker path, including three-stage StringHasher restoration. Add Datum, ShapeBinder, attachment-mode, and PartDesign structure oracles plus offline SDK build plans and CI boundary checks.

native/freecad-naming-probe/shims/Base/Reader.h

@@ -0,0 +1,45 @@
+#pragma once
+
+#include <istream>
+#include <sstream>
+
+namespace Base {
+
+class Reader : public std::istream
+{
+public:
+    Reader()
+        : std::istream(nullptr)
+    {}
+};
+
+class XMLReader
+{
+public:
+    template<typename T>
+    T getAttribute(const char*) const
+    {
+        return T {};
+    }
+
+    bool hasAttribute(const char*) const
+    {
+        return false;
+    }
+
+    void readElement(const char*) {}
+    void readEndElement(const char*) {}
+    void addFile(const char*, void*) {}
+
+    std::istream& beginCharStream()
+    {
+        return stream;
+    }
+
+    int FileVersion = 1;
+
+private:
+    std::istringstream stream;
+};
+
+}  // namespace Base