Build Rust render graph core

Keep hot render state in a generic shared SOA arena and use worker messages only for allocation, graph compilation, loadout changes, and render pacing. Compile external S-expression graphs into upfront WebGPU resources, transient aliases, and reusable render bundles.

Amp-Thread-ID: https://ampcode.com/threads/T-01a01380-b478-77d0-84a0-102880a5c5ae
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>

core/renderer/wgpu.rs

@@ -0,0 +1,53 @@
+pub struct Wgpu {
+    _instance: wgpu::Instance,
+    pub surface: wgpu::Surface<'static>,
+    pub device: wgpu::Device,
+    pub queue: wgpu::Queue,
+    pub config: wgpu::SurfaceConfiguration,
+    pub format: wgpu::TextureFormat,
+    pub width: u32,
+    pub height: u32,
+}
+
+impl Wgpu {
+    pub async fn new(canvas: web_sys::OffscreenCanvas) -> Result<Self, String> {
+        let width = canvas.width();
+        let height = canvas.height();
+        if width == 0 || height == 0 {
+            return Err("CANVAS_SIZE".into());
+        }
+        let instance = wgpu::Instance::new(&wgpu::InstanceDescriptor {
+            backends: wgpu::Backends::BROWSER_WEBGPU,
+            ..Default::default()
+        });
+        let surface = instance
+            .create_surface(wgpu::SurfaceTarget::OffscreenCanvas(canvas))
+            .map_err(|_| "SURFACE")?;
+        let adapter = instance
+            .request_adapter(&wgpu::RequestAdapterOptions {
+                compatible_surface: Some(&surface),
+                ..Default::default()
+            })
+            .await
+            .map_err(|_| "WEBGPU_UNAVAILABLE")?;
+        let (device, queue) = adapter
+            .request_device(&wgpu::DeviceDescriptor::default())
+            .await
+            .map_err(|_| "DEVICE")?;
+        let config = surface
+            .get_default_config(&adapter, width, height)
+            .ok_or("SURFACE")?;
+        let format = config.format;
+        surface.configure(&device, &config);
+        Ok(Self {
+            _instance: instance,
+            surface,
+            device,
+            queue,
+            config,
+            format,
+            width,
+            height,
+        })
+    }
+}