T24a round 1 fix

- overlays::Dialog caps its card at the window, a title bar's height clear
  at each end, and scrolls its body while heading and actions stay; the
  fullscreen body scrolls too; test a_tall_dialog_keeps_its_actions_in_the_window
- ToolCallCard's tool name gives way with an Ellipsis, so time and chevron
  stay in a narrow column; the gallery shows one at 280px
- the Agent script shuts the card it opened, so each theme's shot opens it
- AGENTS: dialogs fit the window

examples/gallery/pages/agent/mod.rs

@@ -24,6 +24,9 @@ const SCRIPT: &[Step] = &[
     Step::Shot("approval"),
     Step::Key("escape"),
     Step::Wait(200),
+    Step::DownAt("agent-call", 60.0, 18.0),
+    Step::UpAt("agent-call", 60.0, 18.0),
+    Step::Wait(200),
 ];
 
 fn render(window: &mut Window, cx: &mut App) -> AnyElement {