fix(ui): keep friends Remove/Add buttons clear of the scrollbar edge

The fill-portion inputs pushed the trailing Remove and Add buttons under the
scrollbar gutter, clipping them. Reserve 12px right clearance on both rows.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -1641,6 +1641,9 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                             .on_press(AppMessage::RemoveFriend(fid))
                             .style(b_style(color_surface, color_maroon, color_text, 6.0))
                             .padding(6),
+                        // Reserve clearance so the button doesn't sit under the
+                        // scrollbar gutter at the right edge.
+                        horizontal_space().width(iced::Length::Fixed(12.0)),
                     ]
                     .spacing(8)
                     .align_y(iced::alignment::Vertical::Center),
@@ -1672,6 +1675,7 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                     .on_press(AppMessage::AddFriend)
                     .style(b_style(color_surface, color_blue, color_text, 6.0))
                     .padding(8),
+                horizontal_space().width(iced::Length::Fixed(12.0)),
             ]
             .spacing(8)
             .align_y(iced::alignment::Vertical::Center),