Improve action menu escape handling

Make the F11 action menu close through a shared close action so Escape and the explicit Close actions menu item follow the same path. Treat Escape-prefixed Up and Down events as close inputs while the action menu is active, which handles termbox InputAlt behavior after pressing Escape. Preserve and restore the user/channel tree selection across action menu open and close, and preserve selection across live tree rebuilds.

Tested with: GOCACHE=/tmp/barnard-go-cache go test ./...

uiterm/tree_test.go

@@ -0,0 +1,86 @@
+package uiterm
+
+import "testing"
+
+type testTreeItem string
+
+func (i testTreeItem) String() string {
+	return string(i)
+}
+
+func (i testTreeItem) TreeItemStyle(fg, bg Attribute, active bool) (Attribute, Attribute) {
+	return fg, bg
+}
+
+func TestTreeRebuildResetsActiveLine(t *testing.T) {
+	t.Parallel()
+
+	tree := Tree{
+		Generator: func(item TreeItem) []TreeItem {
+			if item != nil {
+				return nil
+			}
+			return []TreeItem{testTreeItem("one"), testTreeItem("two"), testTreeItem("three")}
+		},
+	}
+
+	tree.Rebuild()
+	tree.SetActiveLine(2, false)
+	tree.Rebuild()
+
+	if tree.activeLine != 0 {
+		t.Fatalf("expected active line to reset to 0, got %d", tree.activeLine)
+	}
+}
+
+func TestTreeRebuildPreservingActiveItemKeepsMatchingItem(t *testing.T) {
+	t.Parallel()
+
+	items := []TreeItem{testTreeItem("one"), testTreeItem("two"), testTreeItem("three")}
+	tree := Tree{
+		Generator: func(item TreeItem) []TreeItem {
+			if item != nil {
+				return nil
+			}
+			return items
+		},
+	}
+
+	tree.Rebuild()
+	tree.SetActiveLine(1, false)
+	items = []TreeItem{testTreeItem("three"), testTreeItem("one"), testTreeItem("two")}
+	tree.RebuildPreservingActiveItem(func(previous, current TreeItem) bool {
+		return previous.String() == current.String()
+	})
+
+	if tree.activeLine != 2 {
+		t.Fatalf("expected active line to follow matching item to line 2, got %d", tree.activeLine)
+	}
+	if got := tree.ActiveItem().String(); got != "two" {
+		t.Fatalf("expected active item two, got %q", got)
+	}
+}
+
+func TestTreeSetActiveItemSelectsMatchingItem(t *testing.T) {
+	t.Parallel()
+
+	tree := Tree{
+		Generator: func(item TreeItem) []TreeItem {
+			if item != nil {
+				return nil
+			}
+			return []TreeItem{testTreeItem("one"), testTreeItem("two"), testTreeItem("three")}
+		},
+	}
+
+	tree.Rebuild()
+	if ok := tree.SetActiveItem(testTreeItem("three"), func(previous, current TreeItem) bool {
+		return previous.String() == current.String()
+	}); !ok {
+		t.Fatal("expected matching item to be selected")
+	}
+
+	if tree.activeLine != 2 {
+		t.Fatalf("expected active line 2, got %d", tree.activeLine)
+	}
+}