chore: import upstream snapshot with attribution

tests/fixtures/sample.cpp

@@ -0,0 +1,30 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+class Animal {
+public:
+    std::string name;
+    int age;
+
+    Animal(std::string n, int a) : name(n), age(a) {}
+    virtual void speak() { std::cout << name << " speaks" << std::endl; }
+};
+
+class Dog : public Animal {
+public:
+    Dog(std::string n, int a) : Animal(n, a) {}
+    void speak() override { std::cout << name << " barks" << std::endl; }
+    void fetch() { std::cout << name << " fetches" << std::endl; }
+};
+
+void greet(const Animal& animal) {
+    std::cout << "Hello " << animal.name << std::endl;
+}
+
+int main() {
+    Dog d("Rex", 5);
+    d.speak();
+    greet(d);
+    return 0;
+}