Can now build to android apk

Need to fix:
- Remove default android header bar
- Fix rcss styling to work on small screens

src/asset_io.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+#include <string>
+
+inline SDL_IOStream *OpenAssetFile(const std::string &virtual_path) {
+    std::string resolved = virtual_path;
+#if defined(__ANDROID__)
+    if (resolved.rfind("./assets/", 0) == 0) {
+        resolved = resolved.substr(9);
+    } else if (resolved.rfind("assets/", 0) == 0) {
+        resolved = resolved.substr(7);
+    }
+#endif
+    return SDL_IOFromFile(resolved.c_str(), "rb");
+}