refresh: stack al día (vello 0.7 / wgpu 27 / parley 0.6) + motor 3D voxel

Re-sincroniza las fuentes desde el monorepo (estaba en vello 0.5/wgpu 24 y con la
estructura vieja de eventloop) y suma el 3D:

- bump del workspace a vello 0.7 / wgpu 27 / parley 0.6, + accesskit 0.24 /
  accesskit_winit 0.33 / vello_hybrid 0.0.9.
- nuevos crates: llimphi-3d (voxels ray-march + mallas en un depth compartido,
  montable dentro de un View 2D vía set_viewport+scissor) y llimphi-voxel
  (world-gen, personajes, director de escenas) + shared/foreign-vox (puente .vox).
- README: sección "Not just 2D — a 3D voxel engine" + GIF (docs/llimphi_voxel.gif).
- excluido modules/allichay (arrastra deps fuera del alcance del front-door).
- cargo check --workspace: verde.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

llimphi-voxel/examples/desert_demo.rs

@@ -0,0 +1,145 @@
+//! Demo headless del **creador de mundos**: rinde la receta del **desierto**
+//! ([`WorldRecipe::desert`]) — llano de arena, pocas montañas, pocos ríos, cactus.
+//! Es el mundo de apertura del corto.
+//!
+//! `cargo run -p llimphi-voxel --example desert_demo --release -- [dim_xz] [seed]`
+//! → `/tmp/desert.png`
+
+use std::fs::File;
+use std::io::BufWriter;
+
+use llimphi_3d::glam::Vec3;
+use llimphi_3d::{Atmosphere, Camera3d, Scene3d, VoxelRenderer};
+use llimphi_hal::{wgpu, Hal};
+use llimphi_raster::peniko::Color;
+use llimphi_raster::{vello, Renderer};
+use llimphi_voxel::WorldRecipe;
+
+const W: u32 = 960;
+const H: u32 = 540;
+const FMT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;
+
+fn main() {
+    let dim_xz: u32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(160);
+    let seed: u32 = std::env::args().nth(2).and_then(|s| s.parse().ok()).unwrap_or(7);
+    let dy: u32 = (dim_xz * 4 / 10).max(48);
+    let dim = [dim_xz, dy, dim_xz];
+
+    let hal = pollster::block_on(Hal::new(None)).expect("hal");
+    let mut renderer = Renderer::new(&hal).expect("renderer");
+
+    let recipe = WorldRecipe::desert(seed);
+    let grid = recipe.generate(dim);
+
+    let mut vr = VoxelRenderer::new(&hal.device, &hal.queue, FMT, &grid);
+    vr.sun_dir = [0.62, 0.42, 0.28]; // sol más bajo → relieve/sombras de las dunas y cactus
+    vr.atmosphere = Atmosphere {
+        sky_zenith: [92, 146, 208],
+        sky_horizon: [228, 206, 162], // horizonte arenoso/caluroso
+        fog_density: 0.22 / dim_xz as f32, // niebla suave: no lavar el llano
+    };
+
+    // Cámara baja, en 3/4, para leer el llano + los cactus recortados contra el cielo.
+    let camera = Camera3d::orbit(
+        Vec3::new(0.0, dy as f32 * -0.18, 0.0),
+        38_f32.to_radians(),
+        14_f32.to_radians(),
+        dim_xz as f32 * 1.5,
+    );
+
+    let mut scene = Scene3d::new();
+    let pixels = render(&hal, &mut renderer, &mut scene, &mut vr, &camera);
+    write_png(&pixels, "/tmp/desert.png");
+    eprintln!("escrito /tmp/desert.png (desierto {dim_xz}³ seed {seed})");
+}
+
+fn render(
+    hal: &Hal,
+    renderer: &mut Renderer,
+    scene: &mut Scene3d,
+    vr: &mut VoxelRenderer,
+    camera: &Camera3d,
+) -> Vec<u8> {
+    let inter = hal.device.create_texture(&wgpu::TextureDescriptor {
+        label: Some("inter"),
+        size: wgpu::Extent3d { width: W, height: H, depth_or_array_layers: 1 },
+        mip_level_count: 1,
+        sample_count: 1,
+        dimension: wgpu::TextureDimension::D2,
+        format: FMT,
+        usage: wgpu::TextureUsages::STORAGE_BINDING
+            | wgpu::TextureUsages::TEXTURE_BINDING
+            | wgpu::TextureUsages::RENDER_ATTACHMENT
+            | wgpu::TextureUsages::COPY_SRC,
+        view_formats: &[],
+    });
+    let view = inter.create_view(&wgpu::TextureViewDescriptor::default());
+    renderer
+        .render_to_view(hal, &vello::Scene::new(), &view, W, H, Color::from_rgba8(0, 0, 0, 255))
+        .expect("base");
+    let mut enc = hal
+        .device
+        .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: Some("desert") });
+    scene.render(&hal.device, &hal.queue, &mut enc, &view, (W, H), camera, Some(vr), &[]);
+    hal.queue.submit(std::iter::once(enc.finish()));
+    let _ = hal.device.poll(wgpu::PollType::wait_indefinitely());
+    readback(hal, &inter)
+}
+
+fn readback(hal: &Hal, target: &wgpu::Texture) -> Vec<u8> {
+    let unpadded = (W * 4) as usize;
+    let align = wgpu::COPY_BYTES_PER_ROW_ALIGNMENT as usize;
+    let padded = unpadded.div_ceil(align) * align;
+    let buf = hal.device.create_buffer(&wgpu::BufferDescriptor {
+        label: Some("readback"),
+        size: (padded * H as usize) as u64,
+        usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
+        mapped_at_creation: false,
+    });
+    let mut enc = hal
+        .device
+        .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
+    enc.copy_texture_to_buffer(
+        wgpu::TexelCopyTextureInfo {
+            texture: target,
+            mip_level: 0,
+            origin: wgpu::Origin3d::ZERO,
+            aspect: wgpu::TextureAspect::All,
+        },
+        wgpu::TexelCopyBufferInfo {
+            buffer: &buf,
+            layout: wgpu::TexelCopyBufferLayout {
+                offset: 0,
+                bytes_per_row: Some(padded as u32),
+                rows_per_image: Some(H),
+            },
+        },
+        wgpu::Extent3d { width: W, height: H, depth_or_array_layers: 1 },
+    );
+    hal.queue.submit(std::iter::once(enc.finish()));
+    let slice = buf.slice(..);
+    let (tx, rx) = std::sync::mpsc::channel();
+    slice.map_async(wgpu::MapMode::Read, move |r| {
+        let _ = tx.send(r);
+    });
+    let _ = hal.device.poll(wgpu::PollType::wait_indefinitely());
+    rx.recv().unwrap().unwrap();
+    let data = slice.get_mapped_range();
+    let mut pixels = Vec::with_capacity((W * H * 4) as usize);
+    for row in 0..H as usize {
+        let s = row * padded;
+        pixels.extend_from_slice(&data[s..s + unpadded]);
+    }
+    drop(data);
+    buf.unmap();
+    pixels
+}
+
+fn write_png(pixels: &[u8], path: &str) {
+    let file = File::create(path).expect("png");
+    let mut enc = png::Encoder::new(BufWriter::new(file), W, H);
+    enc.set_color(png::ColorType::Rgba);
+    enc.set_depth(png::BitDepth::Eight);
+    let mut wtr = enc.write_header().unwrap();
+    wtr.write_image_data(pixels).unwrap();
+}