agent: Add sound notification when done generating (#31472)

This PR adds the ability to hear a sound notification when the agent is
done generating and/or needs user input. This setting is turned off by
default and can be used together with the visual notification. The
specific sound I'm using here comes from the [Material Design 2 Sound
Library](https://m2.material.io/design/sound/sound-resources.html#).

Release Notes:

- agent: Added the ability to have a sound notification when the agent
is done generating and/or needs user input.

crates/agent/src/agent_configuration.rs

@@ -327,6 +327,45 @@ impl AgentConfiguration {
             )
     }
 
+    fn render_sound_notification(&mut self, cx: &mut Context<Self>) -> impl IntoElement {
+        let play_sound_when_agent_done =
+            AssistantSettings::get_global(cx).play_sound_when_agent_done;
+
+        h_flex()
+            .gap_4()
+            .justify_between()
+            .flex_wrap()
+            .child(
+                v_flex()
+                    .gap_0p5()
+                    .max_w_5_6()
+                    .child(Label::new("Play sound when finished generating"))
+                    .child(
+                        Label::new(
+                            "Hear a notification sound when the agent is done generating changes or needs your input.",
+                        )
+                        .color(Color::Muted),
+                    ),
+            )
+            .child(
+                Switch::new("play-sound-notification-switch", play_sound_when_agent_done.into())
+                    .color(SwitchColor::Accent)
+                    .on_click({
+                        let fs = self.fs.clone();
+                        move |state, _window, cx| {
+                            let allow = state == &ToggleState::Selected;
+                            update_settings_file::<AssistantSettings>(
+                                fs.clone(),
+                                cx,
+                                move |settings, _| {
+                                    settings.set_play_sound_when_agent_done(allow);
+                                },
+                            );
+                        }
+                    }),
+            )
+    }
+
     fn render_general_settings_section(&mut self, cx: &mut Context<Self>) -> impl IntoElement {
         v_flex()
             .p(DynamicSpacing::Base16.rems(cx))
@@ -337,6 +376,7 @@ impl AgentConfiguration {
             .child(Headline::new("General Settings"))
             .child(self.render_command_permission(cx))
             .child(self.render_single_file_review(cx))
+            .child(self.render_sound_notification(cx))
     }
 
     fn render_context_servers_section(