feat(engine): Phase F touch action bar — thumb-reach Undo/Draw/Hint + hold-to-repeat undo

Touch layout (USE_TOUCH_UI_LAYOUT) restructures the bottom action bar
to five buttons: an enlarged Undo / Draw / Hint trio (96x64px targets,
1.35x labels) between compact Menu and Pause. Draw is new — it fires
the same DrawRequestEvent as tapping the stock, so the most frequent
action no longer needs a reach to the top of a tall folded screen.
Help, Modes, and New Game leave the touch bar (they live in Menu ->
System, the Home grid, and Home's hero respectively). Desktop keeps
the seven-button bar unchanged (decision 5: touch-only).

Holding Undo now steps back repeatedly after a 0.45s delay (5.5/s),
each step through the normal request path so the scoring penalty
applies. New self-ambiguous DrawRequestWriters set keeps the ambiguity
gate at zero with the fourth DrawRequestEvent writer.

6 new hud_plugin tests; workspace suite + clippy green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

solitaire_engine/src/hud_plugin/spawn.rs

@@ -400,83 +400,152 @@ pub(super) fn spawn_action_buttons(
             HudActionBar,
         ))
         .with_children(|row| {
-            // The trailing `order` argument feeds `Focusable { group: Hud, order }`
-            // so Tab cycles the action bar in visual reading order.
-            // Undo and Pause are the primary gameplay actions — full brightness.
-            // Menu, Help, Hint, Modes, New are navigation/utility — dimmed.
-            spawn_action_button(
-                row,
-                MenuButton,
-                ACTION_BAR_LABELS[0],
-                None,
-                "Open Stats, Achievements, Profile, Settings, or Leaderboard.",
-                &font,
-                0,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                UndoButton,
-                ACTION_BAR_LABELS[1],
-                Some("U"),
-                "Take back your last move. Costs points and blocks No Undo.",
-                &font,
-                1,
-                TEXT_PRIMARY,
-            );
-            spawn_action_button(
-                row,
-                PauseButton,
-                ACTION_BAR_LABELS[2],
-                Some("Esc"),
-                "Pause the game and freeze the timer.",
-                &font,
-                2,
-                TEXT_PRIMARY,
-            );
-            spawn_action_button(
-                row,
-                HelpButton,
-                ACTION_BAR_LABELS[3],
-                Some("F1"),
-                "Show controls, rules, and keyboard shortcuts.",
-                &font,
-                3,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                HintButton,
-                ACTION_BAR_LABELS[4],
-                Some("H"),
-                "Highlight a suggested move. Cycles through alternatives on repeat taps.",
-                &font,
-                4,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                ModesButton,
-                ACTION_BAR_LABELS[5],
-                None,
-                "Switch modes: Classic, Daily, Zen, Challenge, Time Attack.",
-                &font,
-                5,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                NewGameButton,
-                ACTION_BAR_LABELS[6],
-                Some("N"),
-                "Start a fresh deal. Confirms first if a game is in progress.",
-                &font,
-                6,
-                TEXT_SECONDARY,
-            );
+            if USE_TOUCH_UI_LAYOUT {
+                spawn_touch_action_bar(row, &font);
+            } else {
+                spawn_desktop_action_bar(row, &font);
+            }
         });
 }
 
+/// Phase F touch action bar — five buttons, three of them big.
+///
+/// The core gameplay trio (**Undo · Draw · Hint**) gets enlarged
+/// thumb-reach targets; Menu and Pause stay compact at the edges. The
+/// utility actions the desktop bar carries are reachable elsewhere on
+/// touch and are deliberately absent here: Help lives in Menu → System,
+/// mode switching lives on the Home screen (Phase B), and New Game is
+/// Home's hero button. Draw duplicates the stock-pile tap so the most
+/// frequent action of all no longer requires reaching the top half of a
+/// tall folded screen.
+pub(super) fn spawn_touch_action_bar(row: &mut ChildSpawnerCommands, font: &TextFont) {
+    // The trailing `order` argument feeds `Focusable { group: Hud, order }`
+    // so Tab (external keyboard) cycles the bar in visual reading order.
+    spawn_action_button(
+        row,
+        MenuButton,
+        "Menu",
+        None,
+        "Open Home, Stats, Achievements, Profile, Settings, or Leaderboard.",
+        font,
+        0,
+        TEXT_SECONDARY,
+    );
+    spawn_primary_action_button(
+        row,
+        UndoButton,
+        "Undo",
+        "Take back your last move. Hold to keep undoing. Costs points and blocks No Undo.",
+        font,
+        1,
+    );
+    spawn_primary_action_button(
+        row,
+        DrawButton,
+        "Draw",
+        "Draw from the stock — same as tapping the deck.",
+        font,
+        2,
+    );
+    spawn_primary_action_button(
+        row,
+        HintButton,
+        TOUCH_HINT_LABEL,
+        "Highlight a suggested move. Cycles through alternatives on repeat taps.",
+        font,
+        3,
+    );
+    spawn_action_button(
+        row,
+        PauseButton,
+        "Pause",
+        None,
+        "Pause the game and freeze the timer.",
+        font,
+        4,
+        TEXT_SECONDARY,
+    );
+}
+
+/// Desktop action bar — unchanged by Phase F (decision 5: the touch bar
+/// is touch-only). All seven actions, uniform sizing.
+pub(super) fn spawn_desktop_action_bar(row: &mut ChildSpawnerCommands, font: &TextFont) {
+    // The trailing `order` argument feeds `Focusable { group: Hud, order }`
+    // so Tab cycles the action bar in visual reading order.
+    // Undo and Pause are the primary gameplay actions — full brightness.
+    // Menu, Help, Hint, Modes, New are navigation/utility — dimmed.
+    spawn_action_button(
+        row,
+        MenuButton,
+        "Menu \u{2193}",
+        None,
+        "Open Stats, Achievements, Profile, Settings, or Leaderboard.",
+        font,
+        0,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        UndoButton,
+        "Undo",
+        Some("U"),
+        "Take back your last move. Hold to keep undoing. Costs points and blocks No Undo.",
+        font,
+        1,
+        TEXT_PRIMARY,
+    );
+    spawn_action_button(
+        row,
+        PauseButton,
+        "Pause",
+        Some("Esc"),
+        "Pause the game and freeze the timer.",
+        font,
+        2,
+        TEXT_PRIMARY,
+    );
+    spawn_action_button(
+        row,
+        HelpButton,
+        "Help",
+        Some("F1"),
+        "Show controls, rules, and keyboard shortcuts.",
+        font,
+        3,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        HintButton,
+        "Hint",
+        Some("H"),
+        "Highlight a suggested move. Cycles through alternatives on repeat taps.",
+        font,
+        4,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        ModesButton,
+        "Modes \u{2193}",
+        None,
+        "Switch modes: Classic, Daily, Zen, Challenge, Time Attack.",
+        font,
+        5,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        NewGameButton,
+        "New Game",
+        Some("N"),
+        "Start a fresh deal. Confirms first if a game is in progress.",
+        font,
+        6,
+        TEXT_SECONDARY,
+    );
+}
+
 /// Spawns a single action button as a child of `row`. Each button shares
 /// the same node geometry, idle colour, and `ActionButton` marker so
 /// `paint_action_buttons` can recolour all of them with one query.
@@ -510,13 +579,69 @@ pub(super) fn spawn_action_button<M: Component>(
         None
     };
 
+    let (pad, min_w, min_h) = action_button_metrics();
+    spawn_action_button_sized(
+        row, marker, label, hotkey, tooltip, font, order, text_color, pad, min_w, min_h,
+    );
+}
+
+/// Enlarged variant for the touch bar's core gameplay trio (Phase F):
+/// bigger padding / minimum target and a scaled-up label so Undo, Draw,
+/// and Hint read (and hit) as the primary actions. Hotkey chips are
+/// irrelevant on touch, so the variant takes none.
+pub(super) fn spawn_primary_action_button<M: Component>(
+    row: &mut ChildSpawnerCommands,
+    marker: M,
+    label: &str,
+    tooltip: &'static str,
+    font: &TextFont,
+    order: i32,
+) {
+    let (pad, min_w, min_h) = primary_action_button_metrics();
+    let primary_font = TextFont {
+        font: font.font.clone(),
+        // 1.35× the bar's responsive size, capped so landscape tablets
+        // don't blow the row height out.
+        font_size: (font.font_size * 1.35).min(24.0),
+        ..default()
+    };
+    spawn_action_button_sized(
+        row,
+        marker,
+        label,
+        None,
+        tooltip,
+        &primary_font,
+        order,
+        TEXT_PRIMARY,
+        pad,
+        min_w,
+        min_h,
+    );
+}
+
+/// Shared body of [`spawn_action_button`] / [`spawn_primary_action_button`]
+/// — one place owns the component set so `paint_action_buttons`, tooltips,
+/// and the focus ring treat every bar button identically.
+#[allow(clippy::too_many_arguments)]
+fn spawn_action_button_sized<M: Component>(
+    row: &mut ChildSpawnerCommands,
+    marker: M,
+    label: &str,
+    hotkey: Option<&'static str>,
+    tooltip: &'static str,
+    font: &TextFont,
+    order: i32,
+    text_color: Color,
+    pad: UiRect,
+    min_w: Val,
+    min_h: Val,
+) {
     let hotkey_font = TextFont {
         font: font.font.clone(),
         font_size: TYPE_CAPTION,
         ..default()
     };
-    let (pad, min_w, min_h) = action_button_metrics();
-
     row.spawn((
         marker,
         ActionButton,