Forms: Cmd-Enter submits from any control in a form

Form sets the ElyForm key context and binds secondary-enter to Submit
under it, so a focused tile, chip or button submits too. The prompt
enhancer's wash trims anything but letters and digits from its runs,
its spacing sits on its parts so nothing gaps at rest, and its tests
check that the field takes focus back.

src/generative/tests/mod.rs

@@ -1,7 +1,7 @@
 use std::{cell::RefCell, rc::Rc};
 
 use gpui::{
-    AppContext as _, Context, Entity, IntoElement, KeyBinding, KeyUpEvent, Keystroke,
+    AppContext as _, Context, Entity, Focusable, IntoElement, KeyBinding, KeyUpEvent, Keystroke,
     ParentElement, Render, SharedString, Styled, TestAppContext, VisualTestContext, Window, div,
     px,
 };
@@ -101,6 +101,11 @@ fn enhance_asks_with_the_trimmed_prompt_and_use_this_takes_the_offer(cx: &mut Te
         assert_eq!(view.heard, ["asked a cat", "taken true"]);
         assert_eq!(view.field.read(cx).text(), "a fluffy cat asleep");
     });
+    assert!(field_focused(&view, cx), "the field takes focus back");
+}
+
+fn field_focused(view: &Entity<Enhancing>, cx: &mut VisualTestContext) -> bool {
+    cx.update(|window, cx| view.read(cx).field.focus_handle(cx).is_focused(window))
 }
 
 #[gpui::test]
@@ -119,6 +124,7 @@ fn keep_mine_leaves_the_prompt_as_written(cx: &mut TestAppContext) {
         assert_eq!(view.heard, ["taken false"]);
         assert_eq!(view.field.read(cx).text(), "a cat");
     });
+    assert!(field_focused(&view, cx), "the field takes focus back");
 }
 
 /// Three presets, two ratios, a seed, and every pick heard.