[M5] verify-curated-db.sh + boost recipe (header-only)

scripts/curated-snippets/sdl2.cpp

@@ -0,0 +1,8 @@
+#include <SDL2/SDL.h>
+import std;
+
+int main() {
+    auto* err = SDL_GetError();
+    std::println("sdl2 ok: SDL_GetError() = '{}'", err ? err : "");
+    return 0;
+}