4acf1d821d
- AppHandler::render now receives the current &Frame; its default implementation renders the whole scene automatically via app.render_scene(frame.view()) (Option A). Users can simply not implement render for full auto-rendering. - Add Renderer::render_scene: batch-renders every scene entity in a single render pass. Factored per-mesh draw logic into a private draw_entity helper shared with Renderer::render. - Add App::render_scene(view) delegating to the Renderer. - Fill simple.rs with a real quad (mesh/material/entity) without importing wgpu; the scene now auto-renders via the trait default.