fix(ui): give the segmented control the surface it actually paints on

`segmented` paints its own opaque track — deliberately, since every rung
above it was derived against that ground. But it hardcoded the window
surface, and one of its sixteen call sites is the managed-forward form in
the right panel, which is a sunk `sidebar` rail: the track landed as a
faintly darker box cut out of the column around it, and its hover /
selected / label rungs were measured against a ground that was not there.

Split off `segmented_on`, which takes the `Surface`; `segmented` keeps the
window default the settings sheet wants.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WCb8ZDmvdA5xbVtvs647tD

src/ui/forwards.rs

@@ -358,6 +358,9 @@ impl Tty7App {
     fn forward_form(&self, pane_id: u64, cx: &mut Context<Self>) -> Div {
         let theme = cx.theme();
         let muted = theme.muted_foreground;
+        // The form is inside the right panel, i.e. on the sunk rail — not on the
+        // settings sheet the segmented control otherwise assumes.
+        let sf = cx.global::<crate::ui::presets::Surfaces>().sidebar;
         let kind = self.loopback_panel.mf_kind;
         let editing = self.loopback_panel.mf_editing.is_some();
         let selected = match kind {
@@ -394,7 +397,8 @@ impl Tty7App {
             .pt(px(6.))
             .pb(px(2.))
             .gap(px(5.))
-            .child(self.segmented(
+            .child(self.segmented_on(
+                sf,
                 "ssh-managed-forward-kind",
                 &["Local", "Remote", "Dynamic"],
                 selected,

src/ui/settings.rs

@@ -1204,6 +1204,23 @@ impl Tty7App {
         on_pick: impl Fn(&mut Self, usize, &mut Window, &mut Context<Self>) + 'static,
     ) -> AnyElement {
         let sf = cx.global::<presets::Surfaces>().window;
+        self.segmented_on(sf, id, options, selected, cx, on_pick)
+    }
+
+    /// [`Self::segmented`] for a control that does *not* sit on the settings
+    /// sheet. The track paints its own opaque ground, so it has to be told which
+    /// one: dropped on the right panel's sunk rail, a window-surface track reads
+    /// as a faintly darker box cut out of the column it sits in — and every rung
+    /// above it was derived against the wrong ground.
+    pub(crate) fn segmented_on(
+        &self,
+        sf: presets::Surface,
+        id: &'static str,
+        options: &'static [&'static str],
+        selected: usize,
+        cx: &mut Context<Self>,
+        on_pick: impl Fn(&mut Self, usize, &mut Window, &mut Context<Self>) + 'static,
+    ) -> AnyElement {
         let border = cx.theme().border;
         let on_pick = std::rc::Rc::new(on_pick);
         h_flex()