Unify window presentation and frame-driven shell motion

Share window geometry across overview, resize snapshots and retained closes. Advance close handoffs and group retained rendering by stacking position.

Drive shell motion from surface frames, reuse settled widget content, and synchronize notification materials with each card's fade. Replace physical config keys with duration and bounce, and update documentation and regression coverage.

shell/ferese-shell/src/notification_ui.rs

@@ -148,6 +148,9 @@ impl FereseShell {
     }
 
     pub(super) fn sync_notification_surface(&mut self) -> Task<Message> {
+        // Hidden toast surfaces receive no frame callbacks. Their closes have
+        // no visible transition to finish, so release them immediately.
+        self.notifications.tick();
         if self.notifications.ready {
             self.status.notifications = Some(status::Notifications {
                 count: self.notifications.unread(),
@@ -513,10 +516,36 @@ impl FereseShell {
     }
 
     pub(super) fn view_notifications(&self) -> Element<'_, cosmic::Action<Message>> {
+        motion::frame_driven(
+            self.notifications.motion_revision(),
+            |now| self.view_notifications_at(now),
+            |now| self.notifications.frame_active(now),
+            |now| {
+                if let Some(surface) = &self.notification_surface
+                    && let Some(effects) = &surface.effects
+                {
+                    let _ = effects.set_regions(&surface.regions.lock().unwrap());
+                    let _ = effects.set_region_opacities(
+                        self.notifications
+                            .popup_groups_at(now)
+                            .iter()
+                            .map(|(_, opacity, _)| *opacity),
+                    );
+                }
+            },
+            |now| {
+                self.notifications
+                    .has_finished_closes(now)
+                    .then_some(cosmic::Action::App(Message::NotificationTick))
+            },
+        )
+    }
+
+    pub(super) fn view_notifications_at(&self, now: std::time::Instant) -> Element<'_, cosmic::Action<Message>> {
         if self.notifications.history_open {
             let palette = self.config.theme;
             let surface = self.menu.as_ref();
-            let progress = surface.map_or(1.0, status_ui::OpenMenu::progress);
+            let progress = surface.map_or(1.0, |menu| menu.motion.progress_at(now));
             let opacity = 1.0;
             let color = move |rgba| color_with_opacity(rgba, opacity);
             let primary = color(palette.text_primary);
@@ -751,7 +780,7 @@ impl FereseShell {
             )
         } else {
             let mut cards = column([]).spacing(8);
-            for (notice, opacity, count) in self.notifications.popup_groups() {
+            for (notice, opacity, count) in self.notifications.popup_groups_at(now) {
                 cards = cards.push(self.notification_card(notice, opacity, false, count));
             }
             motion::animated(