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/forms/picks.rs

@@ -150,7 +150,7 @@ pub(crate) fn grid(
         .capture_action(move |_: &Down, window, cx| {
             if count > 0 {
                 cx.stop_propagation();
-                window.focus(&into);
+                window.focus(&into, cx);
             }
         })
         .capture_action(move |_: &Enter, window, cx| {
@@ -231,7 +231,7 @@ pub(crate) fn grid(
                 })
                 .collect()
         })
-        .track_scroll(scroll)
+        .track_scroll(&scroll)
         .h(theme.list_max_height());
         div()
             .track_focus(&focus)