Initial project scaffold

Sets up eframe/egui app with basic menu bar and placeholder viewport. Adds Rhai scripting dependency for future game object scripting system.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.rs

@@ -0,0 +1,34 @@
+use eframe::egui;
+
+fn main() -> eframe::Result<()> {
+    let options = eframe::NativeOptions::default();
+    eframe::run_native(
+        "Viberogue",
+        options,
+        Box::new(|_cc| Ok(Box::new(App::default()))),
+    )
+}
+
+#[derive(Default)]
+struct App;
+
+impl eframe::App for App {
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        egui::TopBottomPanel::top("menu_bar").show(ctx, |ui| {
+            egui::MenuBar::new().ui(ui, |ui| {
+                ui.menu_button("File", |ui| {
+                    if ui.button("Exit").clicked() {
+                        ctx.send_viewport_cmd(egui::ViewportCommand::Close);
+                    }
+                });
+            });
+        });
+
+        egui::CentralPanel::default().show(ctx, |ui| {
+            let rect = ui.available_rect_before_wrap();
+            let center = rect.center();
+            let square = egui::Rect::from_center_size(center, egui::vec2(200.0, 200.0));
+            ui.painter().rect_filled(square, 0.0, egui::Color32::BLUE);
+        });
+    }
+}