core: support OSC 9 and OSC 777 for showing desktop notifications

src/apprt/structs.zig

@@ -50,3 +50,13 @@ pub const ClipboardRequest = union(ClipboardRequestType) {
     /// A request to write clipboard contents via OSC 52.
     osc_52_write: Clipboard,
 };
+
+/// A desktop notification.
+pub const DesktopNotification = struct {
+    /// The title of the notification. May be an empty string to not show a
+    /// title.
+    title: []const u8,
+
+    /// The body of a notification. This will always be shown.
+    body: []const u8,
+};