Initialize camera to follow root body on startup

src/main.cpp

@@ -36,12 +36,21 @@ void run_gui_simulation(SimulationState* sim) {
     RenderState render_state;
     setup_camera(&render_state);
 
+    // Find root body (body with parent_index == -1)
+    int root_body_index = -1;
+    for (int i = 0; i < sim->body_count; i++) {
+        if (sim->bodies[i].parent_index == -1) {
+            root_body_index = i;
+            break;
+        }
+    }
+
     // Initialize UI state
-    render_state.selected_body_index = -1;  // No selection initially
+    render_state.selected_body_index = root_body_index >= 0 ? root_body_index : -1;
     render_state.previous_selected_body = -1;  // Previous selected body index
     render_state.body_list_scroll = 0;     // Initial scroll position
-    render_state.body_list_active = -1;    // No active item initially
-    render_state.camera_follow_body = false; // Camera not following initially
+    render_state.body_list_active = root_body_index >= 0 ? root_body_index : -1;  // Sync with selected body
+    render_state.camera_follow_body = root_body_index >= 0; // Follow root body if found
     render_state.camera_offset = (Vector3){ 0, 50, 100 }; // Default offset
     render_state.was_following_body = false;