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/i18n/tests/mod.rs

@@ -206,14 +206,7 @@ mod shown {
 
     #[test]
     fn text_sits_against_the_reading_side() {
-        let side = |direction: Direction| {
-            direction
-                .align(div())
-                .style()
-                .text
-                .as_ref()
-                .and_then(|text| text.text_align)
-        };
+        let side = |direction: Direction| direction.align(div()).style().text.text_align;
         assert_eq!(side(Direction::Ltr), Some(gpui::TextAlign::Left));
         assert_eq!(side(Direction::Rtl), Some(gpui::TextAlign::Right));
     }