fix(palette): keep Tab inside the command palette

The palette is walked with the arrows and run with Enter; Tab has no job
there. Root's focus walker had one for it anyway, and sent it out of the
modal onto whichever chrome tile sat behind the scrim — the New Tab plus,
the panel toggle — which lit up with a focus ring the palette had no way to
take back.

Tab and Shift-Tab bind to `NoAction` in the palette's own context, which is
deeper than Root's and stops the search before the walker is reached.

src/ui/keymap.rs

@@ -33,6 +33,11 @@ pub fn init(cx: &mut App) {
         SwitcherAcrossBack,
         Some("Switcher"),
     ));
+    // The palette has nowhere for Tab to go — the arrows walk the list and
+    // Enter runs it — but Root's focus walker still had somewhere to send it:
+    // out of the modal, onto whichever chrome tile is behind it, ring and all.
+    bindings.push(KeyBinding::new("tab", NoAction {}, Some("Palette")));
+    bindings.push(KeyBinding::new("shift-tab", NoAction {}, Some("Palette")));
     cx.bind_keys(bindings);
     cx.set_global(BoundKeystrokes(bound_keystrokes(&effective)));
 

src/ui/palette.rs

@@ -1137,6 +1137,7 @@ impl Render for PaletteView {
             .justify_center()
             .pt(px(120.))
             .bg(scrim)
+            .key_context("Palette")
             .on_key_down(cx.listener(|this, ev: &gpui::KeyDownEvent, _window, cx| {
                 let ks = &ev.keystroke;
                 if is_edit_gesture(ks) {