v0.1.0: software map renderer + SDL3 window viewer

src/ui/ra3.ui.null.cppm

@@ -0,0 +1,24 @@
+module;
+
+#include <string>
+
+export module ra3.ui;
+
+export import ra3.core;
+import ra3.render;
+
+/**
+ * Fallback viewer used when the build has no SDL3. It never opens a window;
+ * the caller should write an offscreen image instead.
+ */
+export namespace ra3::ui {
+    /** Window parameters (mirrors the SDL backend). */
+    struct viewer_options {
+        std::string title = "OpenRA3";
+        int width = 1024;
+        int height = 768;
+    };
+
+    /** Always returns false: this build has no windowing backend. */
+    [[nodiscard]] inline auto run_viewer(const ra3::render::image &, const viewer_options &) -> bool { return false; }
+}