T02 typography: text styles, keys, formatters, fit, links, math, motion text

Headings to overlines, Code, Kbd and KbdCombo on gpui keystrokes,
Highlight, MiddleEllipsis and EllipsisTooltip, links, eight formatted
values on jiff with a typographic minus, CopyableText, SelectableText,
Emoji, a TeX subset, rolling AnimatedNumber, Typewriter, tonal
GradientText, ShimmerText. Gallery probes now hug their targets.
Codex gpt-6-astra (max): PASS in round 2.

src/typography/emoji.rs

@@ -0,0 +1,49 @@
+use gpui::{App, IntoElement, ParentElement, RenderOnce, SharedString, Styled, Window, div};
+
+use crate::theme::{ActiveTheme, TextSize};
+
+/// One emoji in the system color font.
+#[derive(IntoElement)]
+pub struct Emoji {
+    glyph: SharedString,
+    size: TextSize,
+}
+
+impl Emoji {
+    pub fn new(glyph: impl Into<SharedString>) -> Self {
+        Self {
+            glyph: glyph.into(),
+            size: TextSize::Lg,
+        }
+    }
+
+    /// GitHub shortcode without colons; `None` if unknown.
+    pub fn shortcode(code: &str) -> Option<Self> {
+        emojis::get_by_shortcode(code).map(|emoji| Self::new(emoji.as_str()))
+    }
+
+    pub fn size(mut self, size: TextSize) -> Self {
+        self.size = size;
+        self
+    }
+}
+
+impl RenderOnce for Emoji {
+    fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
+        div()
+            .text_size(cx.theme().text_size(self.size))
+            .child(self.glyph)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Emoji;
+
+    #[test]
+    fn shortcodes_resolve_or_refuse() {
+        let glyph = Emoji::shortcode("sparkles").map(|emoji| emoji.glyph.to_string());
+        assert_eq!(glyph.as_deref(), Some("✨"));
+        assert!(Emoji::shortcode("not_an_emoji_name").is_none());
+    }
+}