Port · Build: Zed's gpui at 1a28cff

gpui and gpui_platform now come from Zed's repo by git at 1a28cff,
the code gpui-pre 0.3.7 republishes, so the gallery can later build
for the browser. gpui takes stacker, as 0.2.2 always did, and
gpui_platform takes font-kit, without which macOS draws no text;
runtime_shaders moves to gpui_platform.

The API moved: focus, blur and Tab steps take cx, Corner is Anchor,
shaped lines paint with an alignment, defer_draw takes a content
mask, the inspector registers a factory, async updates return their
value, and wrapped lines are shared, not cloned. Updates through a
window context go through the window, so a closed window still ends
them as it did.

Where the new gpui behaves differently, Ely keeps its old intent.
Holds and reveals under a resting pointer survive typing through
gpui's input-modality-independent hover; previews the keyboard also
moves keep the default, and the calendar's leave ignores a key press.
Enter reaches a button inside the code editor, since gpui now arms a
key click on the press. The event logger skips a lone modifier. A
video and an image grid keep their shape in a flex column under
taffy 0.13, as a picture does.

AGENTS.md records the new stack and the rules this port changes; the
rest of the old gpui and taffy rules are re-tested in T44c.

src/typography/text.rs

@@ -10,20 +10,14 @@ use crate::theme::{ActiveTheme, Palette, TextSize};
 /// Tabular numerals, so digits line up in columns.
 pub fn tabular<E: Styled>(mut element: E) -> E {
     let features = FontFeatures(Arc::new(vec![("tnum".into(), 1)]));
-    element
-        .text_style()
-        .get_or_insert_with(Default::default)
-        .font_features = Some(features);
+    element.text_style().font_features = Some(features);
     element
 }
 
 /// Each character drawn as itself, without ligatures: `==` stays two signs in encoded text and keys.
 pub fn literal<E: Styled>(mut element: E) -> E {
     let features = FontFeatures(Arc::new(vec![("calt".into(), 0), ("liga".into(), 0)]));
-    element
-        .text_style()
-        .get_or_insert_with(Default::default)
-        .font_features = Some(features);
+    element.text_style().font_features = Some(features);
     element
 }