feat(k-ui): first slice: App trait + run loop, builders (column/row/text/button), flex layout, theme tokens (Whimsy Dark), tiny-skia + fontdue render (Noto Sans Latin subset), keyboard focus ring; tally demo; manifest memory key (pm spawns with it)

crates/apps/tally/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "tally"
+version = "0.1.0"
+edition = "2024"
+
+[[bin]]
+name = "tally"
+test = false
+bench = false
+
+[dependencies]
+libkos = { workspace = true }
+k-ui = { workspace = true }

crates/apps/tally/manifest.toml

@@ -0,0 +1,10 @@
+[app]
+id      = "kos.tally"
+name    = "Tally"
+version = "1.0.0"
+binary  = "tally"
+author  = "K-OS"
+memory  = "3 MiB"
+
+[capabilities]
+required = ["display"]

crates/apps/tally/src/main.rs

@@ -0,0 +1,61 @@
+//! A count, and buttons to change it: the first K-UI app. Tab and the
+//! arrows move between the buttons, Enter presses, Escape leaves.
+
+#![no_std]
+#![forbid(unsafe_code)]
+#![no_main]
+
+extern crate alloc;
+extern crate libkos;
+
+use alloc::format;
+use k_ui::{App, ButtonVariant, Element, Spacing, TextColour, TextStyle, button, column, row, text};
+
+#[derive(Clone, Copy)]
+enum Event {
+    Add,
+    Subtract,
+    Reset,
+}
+
+struct Tally(i64);
+
+impl App for Tally {
+    type Event = Event;
+
+    fn init() -> Self {
+        Tally(0)
+    }
+
+    fn update(&mut self, event: Event) {
+        match event {
+            Event::Add => self.0 += 1,
+            Event::Subtract => self.0 -= 1,
+            Event::Reset => self.0 = 0,
+        }
+    }
+
+    fn view(&self) -> Element<Event> {
+        let mut buttons = row()
+            .gap(Spacing::Md)
+            .child(button("Subtract", Event::Subtract))
+            .child(button("Add", Event::Add).variant(ButtonVariant::Primary));
+        if self.0 != 0 {
+            buttons = buttons.child(button("Reset", Event::Reset).variant(ButtonVariant::Destructive));
+        }
+        column()
+            .padding(Spacing::Xl)
+            .gap(Spacing::Lg)
+            .child(text("Tally").style(TextStyle::Heading))
+            .child(text(format!("{}", self.0)).style(TextStyle::Subheading).colour(TextColour::Accent))
+            .child(buttons)
+            .child(text("Tab moves, Enter presses, Esc leaves").style(TextStyle::Caption).colour(TextColour::Secondary))
+            .into()
+    }
+}
+
+libkos::entry!(main);
+
+fn main() {
+    k_ui::run::<Tally>();
+}