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/dashboard/tests.rs

@@ -95,7 +95,7 @@ fn press(key: &str, cx: &mut VisualTestContext) {
 #[gpui::test]
 fn arrows_step_a_focused_tile_past_its_neighbours_and_shift_grows_it(cx: &mut TestAppContext) {
     let (host, cx) = wall(cx);
-    cx.update(|window, _| window.focus_next());
+    cx.update(|window, cx| window.focus_next(cx));
     settle(cx);
     press("down", cx);
     assert_eq!(place(&host, "a", cx), (0, 4, 6, 2), "a went below c");
@@ -115,7 +115,7 @@ fn arrows_step_a_focused_tile_past_its_neighbours_and_shift_grows_it(cx: &mut Te
 fn arrows_in_a_control_inside_a_card_leave_the_tiles_where_they_are(cx: &mut TestAppContext) {
     let (host, cx) = wall(cx);
     let inside = host.read_with(cx, |wall, _| wall.inside.clone());
-    cx.update(|window, _| window.focus(&inside));
+    cx.update(|window, cx| window.focus(&inside, cx));
     settle(cx);
     press("right", cx);
     press("down", cx);
@@ -168,9 +168,9 @@ fn said(host: &Entity<Board>, cx: &mut VisualTestContext) -> Vec<String> {
 }
 
 fn tab(stops: usize, cx: &mut VisualTestContext) {
-    cx.update(|window, _| {
-        window.blur();
-        (0..stops).for_each(|_| window.focus_next());
+    cx.update(|window, cx| {
+        window.blur(cx);
+        (0..stops).for_each(|_| window.focus_next(cx));
     });
     settle(cx);
 }