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>

widgets/scroll/examples/scroll_avanzado.rs

@@ -0,0 +1,206 @@
+//! Showcase de scroll avanzado (Tier 5): **app-bar colapsable** (sliver) +
+//! lista scrolleable + **inercia (fling)**. Un único `offset` en el Model
+//! maneja el colapso del header y el scroll del cuerpo; los botones "Fling"
+//! sueltan una velocidad que decae con [`fling_step`] vía un ticker periódico.
+//!
+//! Corré con:
+//! ```text
+//! cargo run -p llimphi-widget-scroll --example scroll_avanzado --release
+//! ```
+
+use std::time::Duration;
+
+use llimphi_theme::Theme;
+use llimphi_ui::llimphi_layout::taffy::{
+    prelude::{length, percent, FlexDirection, Size, Style},
+    AlignItems, JustifyContent, Rect,
+};
+use llimphi_ui::{App, Handle, View};
+use llimphi_widget_scroll::{
+    clamp_offset, fling_settled, fling_step, sliver_app_bar, sliver_max_offset, ScrollPalette,
+    FLING_FRICTION,
+};
+
+const HEADER_MAX: f32 = 200.0;
+const HEADER_MIN: f32 = 56.0;
+const VIEWPORT: f32 = 560.0;
+const ROW_H: f32 = 46.0;
+const N_ROWS: usize = 40;
+const CONTENT_LEN: f32 = N_ROWS as f32 * ROW_H;
+const DT: f32 = 1.0 / 60.0;
+
+#[derive(Clone)]
+enum Msg {
+    /// Delta de scroll en px (rueda / arrastre de barra) a sumar al offset.
+    ScrollBy(f32),
+    /// Soltar una inercia con esta velocidad inicial (px/s).
+    Fling(f32),
+    /// Tick del ticker: avanza la inercia si hay.
+    Tick,
+}
+
+struct Model {
+    offset: f32,
+    velocity: f32,
+    theme: Theme,
+}
+
+fn max_off() -> f32 {
+    sliver_max_offset(CONTENT_LEN, VIEWPORT, HEADER_MAX, HEADER_MIN)
+}
+
+struct Demo;
+
+impl App for Demo {
+    type Model = Model;
+    type Msg = Msg;
+
+    fn title() -> &'static str {
+        "llimphi · scroll avanzado (sliver + fling)"
+    }
+
+    fn initial_size() -> (u32, u32) {
+        (720, VIEWPORT as u32)
+    }
+
+    fn init(handle: &Handle<Self::Msg>) -> Self::Model {
+        // Ticker de inercia ~60 fps (mismo patrón que `approach`).
+        handle.spawn_periodic(Duration::from_millis(16), || Msg::Tick);
+        Model { offset: 0.0, velocity: 0.0, theme: Theme::dark() }
+    }
+
+    fn update(mut model: Self::Model, msg: Self::Msg, _: &Handle<Self::Msg>) -> Self::Model {
+        match msg {
+            Msg::ScrollBy(d) => {
+                model.velocity = 0.0; // un scroll manual corta la inercia
+                model.offset = clamp_offset(model.offset + d, max_off() + VIEWPORT, VIEWPORT);
+                // (clamp_offset usa content/viewport; acá el "content" efectivo
+                // es max_off + viewport, así max_offset(...) == max_off.)
+            }
+            Msg::Fling(v) => model.velocity = v,
+            Msg::Tick => {
+                if model.velocity != 0.0 {
+                    let (v, delta) = fling_step(model.velocity, DT, FLING_FRICTION);
+                    model.offset =
+                        clamp_offset(model.offset + delta, max_off() + VIEWPORT, VIEWPORT);
+                    // Frenar en los topes o al asentarse.
+                    if fling_settled(v) || model.offset <= 0.0 || model.offset >= max_off() {
+                        model.velocity = 0.0;
+                    } else {
+                        model.velocity = v;
+                    }
+                }
+            }
+        }
+        model
+    }
+
+    fn view(model: &Self::Model) -> View<Self::Msg> {
+        let t = &model.theme;
+        let pal = ScrollPalette::from_theme(t);
+
+        // Lista (cuerpo del sliver): filas alternadas.
+        let rows: Vec<View<Msg>> = (0..N_ROWS)
+            .map(|i| {
+                let bg = if i % 2 == 0 { t.bg_panel } else { t.bg_panel_alt };
+                View::new(Style {
+                    size: Size { width: percent(1.0), height: length(ROW_H) },
+                    align_items: Some(AlignItems::Center),
+                    padding: Rect { left: length(20.0), right: length(20.0), top: length(0.0), bottom: length(0.0) },
+                    ..Default::default()
+                })
+                .fill(bg)
+                .text(format!("Fila {:02}", i + 1), 18.0, t.fg_text)
+            })
+            .collect();
+        let list = View::new(Style {
+            flex_direction: FlexDirection::Column,
+            size: Size { width: percent(1.0), height: length(CONTENT_LEN) },
+            ..Default::default()
+        })
+        .children(rows);
+
+        let theme = t.clone();
+        let sliver = sliver_app_bar(
+            model.offset,
+            HEADER_MAX,
+            HEADER_MIN,
+            move |frac| header(&theme, frac),
+            list,
+            CONTENT_LEN,
+            VIEWPORT,
+            Msg::ScrollBy,
+            &pal,
+        );
+
+        View::new(Style {
+            size: Size { width: percent(1.0), height: percent(1.0) },
+            ..Default::default()
+        })
+        .fill(t.bg_app)
+        .children(vec![sliver])
+    }
+}
+
+/// Header colapsable: el título encoge con `frac` y el subtítulo + botones de
+/// fling se desvanecen al colapsar (el `clip` del header los recorta).
+fn header(t: &Theme, frac: f32) -> View<Msg> {
+    let title_size = 34.0 - 14.0 * frac; // 34 → 20
+    // Fondo que se aclara al colapsar (de accent a panel).
+    let title_row = View::new(Style {
+        flex_direction: FlexDirection::Row,
+        size: Size { width: percent(1.0), height: length(HEADER_MIN) },
+        align_items: Some(AlignItems::Center),
+        justify_content: Some(JustifyContent::SpaceBetween),
+        padding: Rect { left: length(20.0), right: length(16.0), top: length(0.0), bottom: length(0.0) },
+        ..Default::default()
+    })
+    .children(vec![
+        View::new(Style { ..Default::default() })
+            .text("Scroll avanzado", title_size, t.fg_text),
+        fling_buttons(t),
+    ]);
+
+    let subtitle = View::new(Style {
+        size: Size { width: percent(1.0), height: length(28.0) },
+        align_items: Some(AlignItems::Center),
+        padding: Rect { left: length(20.0), right: length(20.0), top: length(0.0), bottom: length(0.0) },
+        ..Default::default()
+    })
+    .alpha(1.0 - frac) // se desvanece al colapsar
+    .text("Tier 5 · app-bar colapsable + inercia · rueda para scrollear", 15.0, t.fg_muted);
+
+    View::new(Style {
+        flex_direction: FlexDirection::Column,
+        size: Size { width: percent(1.0), height: length(HEADER_MAX) },
+        ..Default::default()
+    })
+    .fill(t.bg_panel_alt)
+    .children(vec![title_row, subtitle])
+}
+
+fn fling_buttons(t: &Theme) -> View<Msg> {
+    let btn = |label: &str, v: f32| {
+        View::new(Style {
+            size: Size { width: length(96.0), height: length(34.0) },
+            align_items: Some(AlignItems::Center),
+            justify_content: Some(JustifyContent::Center),
+            ..Default::default()
+        })
+        .fill(t.bg_button)
+        .hover_fill(t.bg_button_hover)
+        .radius(8.0)
+        .text(label.to_string(), 15.0, t.fg_text)
+        .on_click(Msg::Fling(v))
+    };
+    View::new(Style {
+        flex_direction: FlexDirection::Row,
+        gap: Size { width: length(8.0), height: length(0.0) },
+        ..Default::default()
+    })
+    .children(vec![btn("Fling ▲", -2600.0), btn("Fling ▼", 2600.0)])
+}
+
+fn main() {
+    llimphi_ui::run::<Demo>();
+}