Add audio output switching and fix the workspace trail

The control panel lists PipeWire sinks and sets the default, moving
playing streams so the change is immediate. The workspace pill starts
on switch without a layout wait, measures against the Fixed host so it
stays centered on the digit, and ignores row-wide bounds that used to
stretch it across several chips.

src/main.rs

@@ -99,6 +99,8 @@ pub struct App {
     panel_vol_slider: gtk4::Scale,
     panel_bright_slider: gtk4::Scale,
     panel_loading: Rc<Cell<bool>>,
+    sink_box: gtk4::Box,
+    sink_section: gtk4::Box,
 
     // ── Tray ──────────────────────────────────────────────────────────────
     tray_section: gtk4::Box,
@@ -517,6 +519,18 @@ impl SimpleComponent for App {
         let panel_vol_slider = vol_row.1.clone();
         panel_inner.append(&vol_row.0);
 
+        let sink_section = gtk4::Box::new(gtk4::Orientation::Vertical, 0);
+        sink_section.add_css_class("control-panel-section");
+        let sink_header = gtk4::Label::new(Some("OUTPUT"));
+        sink_header.add_css_class("control-panel-header");
+        sink_header.set_xalign(0.0);
+        sink_header.set_margin_top(6);
+        let sink_box = gtk4::Box::new(gtk4::Orientation::Vertical, 0);
+        sink_section.append(&sink_header);
+        sink_section.append(&sink_box);
+        sink_section.set_visible(false);
+        panel_inner.append(&sink_section);
+
         let bright_row = build_slider_row("bl", 0.0, 1.0, 0.02);
         let panel_bright_slider = bright_row.1.clone();
         panel_inner.append(&bright_row.0);
@@ -747,6 +761,8 @@ impl SimpleComponent for App {
             panel_vol_slider,
             panel_bright_slider,
             panel_loading,
+            sink_box,
+            sink_section,
             tray_section,
             tray_sep,
             tray_box,
@@ -1033,6 +1049,7 @@ impl SimpleComponent for App {
                 self.panel_vol_slider.set_value(data.volume);
                 self.panel_bright_slider.set_value(data.brightness);
                 self.panel_loading.set(false);
+                self.rebuild_sinks(&data.sinks, &sender);
             }
             AppInput::WidgetsUpdate(specs) => {
                 self.reconcile_widgets(specs);
@@ -1129,6 +1146,40 @@ impl App {
         }
     }
 
+    fn rebuild_sinks(
+        &mut self,
+        sinks: &[bar::control::AudioSink],
+        sender: &ComponentSender<Self>,
+    ) {
+        while let Some(child) = self.sink_box.first_child() {
+            self.sink_box.remove(&child);
+        }
+        self.sink_section.set_visible(!sinks.is_empty());
+        for (i, sink) in sinks.iter().enumerate() {
+            let row = gtk4::Button::new();
+            row.add_css_class("flat");
+            row.add_css_class("wifi-popover-row");
+            row.add_css_class("sink-row");
+            if sink.is_default {
+                row.add_css_class("wifi-popover-row-active");
+            }
+            stagger_row(&row, i);
+            let lbl = gtk4::Label::new(Some(&sink.description));
+            lbl.set_xalign(0.0);
+            lbl.set_hexpand(true);
+            lbl.set_ellipsize(gtk4::pango::EllipsizeMode::End);
+            lbl.set_max_width_chars(22);
+            lbl.set_valign(gtk4::Align::Center);
+            row.set_child(Some(&lbl));
+            let name = sink.name.clone();
+            let sender = sender.clone();
+            row.connect_clicked(move |_| {
+                bar::control::spawn_set_sink(name.clone(), sender.clone());
+            });
+            self.sink_box.append(&row);
+        }
+    }
+
     fn apply_wifi_label(&self) {
         let label = match &self.wifi_profile {
             Some(p) => format!("{p} · {}", self.current_ssid),