fix(engine): modal action buttons wrap to next row on narrow screens

On high-DPI Android (Pixel 7: 420 DPI → ~411 dp logical width), the
modal card fits at ~363 dp wide. The stats modal's three-button row
("Watch replay" + "Copy share link" + "Done") totals ~455 dp, causing
text to wrap inside each button (2–3 lines per button label).

Added flex_wrap: FlexWrap::Wrap + row_gap: VAL_SPACE_2 to
spawn_modal_actions so buttons that don't fit flow onto a second line
as whole units instead of wrapping text inside them. Affects all modals
uniformly; desktop (wide modal) is unaffected since buttons fit in one
line with room to spare.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/ui_modal.rs

@@ -296,6 +296,10 @@ pub fn spawn_modal_body_text(
 
 /// Spawns the bottom actions row — flex-row with primary right-aligned.
 /// The closure populates the row's buttons via `spawn_modal_button`.
+///
+/// `flex_wrap: Wrap` lets the row reflow onto a second line when buttons
+/// collectively exceed the modal width on narrow screens (e.g. high-DPI
+/// Android where the logical viewport is ~411 dp).
 pub fn spawn_modal_actions<F>(parent: &mut ChildSpawnerCommands, build_buttons: F)
 where
     F: FnOnce(&mut ChildSpawnerCommands),
@@ -305,7 +309,9 @@ where
             ModalActions,
             Node {
                 flex_direction: FlexDirection::Row,
+                flex_wrap: FlexWrap::Wrap,
                 column_gap: VAL_SPACE_3,
+                row_gap: VAL_SPACE_2,
                 justify_content: JustifyContent::FlexEnd,
                 margin: UiRect::top(VAL_SPACE_2),
                 ..default()