fix: use PollType::Wait and remove pre_present_notify (subtask 2.4 fixes)

docs/01-rainbow-triangle.md

@@ -955,7 +955,7 @@ fn render(&mut self) {
         wgpu::SurfaceStatus::Success(surface_texture)
         | wgpu::SurfaceStatus::Suboptimal(surface_texture) => {
             // Drive GPU work: shader compilation, memory allocation, fence signaling
-            if let Err(e) = self.device.poll(wgpu::Maintain::Wait) {
+            if let Err(e) = self.device.poll(wgpu::PollType::Wait { submission_index: None, timeout: None }) {
                 log::error!("Device poll failed: {e}");
                 return;
             }
@@ -1038,7 +1038,7 @@ from the [swapchain](concepts/GLOSSARY.md#swapchain). The swapchain cycles throu
 2–3 pre-allocated back buffers. This call returns immediately if a buffer is
 available; it does not block on the GPU.
 
-**`device.poll(wgpu::Maintain::Wait)`** — **Synchronous** call that drives
+**`device.poll(wgpu::PollType::Wait { submission_index: None, timeout: None })`** — **Synchronous** call that drives
 in-flight GPU work to completion: shader compilation fences, memory allocation,
 and queue signaling. Without this, resources accumulate because the device does
 not reclaim finished work. Called once per frame. Returns
@@ -1182,10 +1182,6 @@ buffer from "render target" to "front buffer" on the next vsync.
   Check logs for the description. This is a programming error, not a runtime
   condition.
 
-Note: `pre_present_notify()` does **not** exist in wgpu 29. Do not call it. The
-device polling via `device.poll()` is the only frame synchronization mechanism
-you need.
-
 ## S8: Handling Window Resize
 
 WHY `surface.configure()` on resize: The swapchain allocates back buffers at a