feat(engine,data): add tap-to-select touch input mode (#70)

- Add TouchInputMode enum (OneTap | TapToSelect) to solitaire_data settings
- Create TouchSelectionPlugin with TouchSelectionState resource and highlight
- Branch handle_double_tap: OneTap → existing auto-move, TapToSelect → two-tap flow
- Add Settings UI toggle row (Touch Input Mode) with TouchInputModeText marker
- Register TouchSelectionPlugin in CoreGamePlugin

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

solitaire_engine/src/input_plugin.rs

@@ -48,7 +48,9 @@ use crate::radial_menu::RightClickRadialState;
 use crate::replay_playback::ReplayPlaybackState;
 use crate::resources::{DragState, GameInputConsumedResource, GameStateResource, HintCycleIndex};
 use crate::selection_plugin::SelectionState;
+use crate::settings_plugin::SettingsResource;
 use crate::time_attack_plugin::TimeAttackResource;
+use crate::touch_selection_plugin::TouchSelectionState;
 use crate::ui_theme::{MOTION_DRAG_REJECT_SECS, STATE_SUCCESS, STATE_WARNING};
 use solitaire_core::game_state::DrawMode;
 
@@ -1503,11 +1505,15 @@ fn handle_double_tap(
     radial: Option<Res<RightClickRadialState>>,
     drag: Res<DragState>,
     game: Res<GameStateResource>,
+    settings: Option<Res<SettingsResource>>,
+    mut touch_selection: Option<ResMut<TouchSelectionState>>,
     mut moves: MessageWriter<MoveRequestEvent>,
     mut rejected: MessageWriter<MoveRejectedEvent>,
     mut commands: Commands,
     mut card_sprites: Query<(Entity, &CardEntity, &mut Sprite)>,
 ) {
+    use solitaire_data::settings::TouchInputMode;
+
     if paused.is_some_and(|p| p.0) {
         return;
     }
@@ -1524,6 +1530,10 @@ fn handle_double_tap(
         return;
     }
 
+    let tap_to_select = settings
+        .as_ref()
+        .is_some_and(|s| s.0.touch_input_mode == TouchInputMode::TapToSelect);
+
     for event in touch_events.read() {
         if event.id != active_id || event.phase != TouchPhase::Ended {
             continue;
@@ -1533,10 +1543,10 @@ fn handle_double_tap(
         let Some(&top_card_id) = drag.cards.last() else {
             return;
         };
-        let Some(ref pile) = drag.origin_pile else {
+        let Some(ref tapped_pile) = drag.origin_pile else {
             return;
         };
-        let Some(pile_cards) = game.0.piles.get(pile) else {
+        let Some(pile_cards) = game.0.piles.get(tapped_pile) else {
             return;
         };
 
@@ -1547,6 +1557,34 @@ fn handle_double_tap(
             return;
         }
 
+        // --- Tap-to-select mode ---
+        if tap_to_select {
+            if let Some(ref mut sel) = touch_selection {
+                if let Some((ref source_pile, ref source_cards)) = sel.selected.clone() {
+                    // Second tap: this is the destination.
+                    if tapped_pile == source_pile {
+                        // Re-tap on selected source → cancel.
+                        sel.clear();
+                        return;
+                    }
+                    // Attempt the move. MoveRequestEvent carries validation;
+                    // a rejection will fire MoveRejectedEvent automatically.
+                    moves.write(MoveRequestEvent {
+                        from: source_pile.clone(),
+                        to: tapped_pile.clone(),
+                        count: source_cards.len(),
+                    });
+                    sel.clear();
+                    return;
+                }
+                // First tap: select the source.
+                sel.set(tapped_pile.clone(), drag.cards.clone());
+            }
+            return;
+        }
+
+        // --- One-tap auto-move (original behaviour) ---
+
         // Priority 1: move single top card.
         if let Some(dest) = best_destination(top_card, &game.0) {
             for (entity, ce, mut sprite) in card_sprites.iter_mut() {
@@ -1559,7 +1597,7 @@ fn handle_double_tap(
                 }
             }
             moves.write(MoveRequestEvent {
-                from: pile.clone(),
+                from: tapped_pile.clone(),
                 to: dest,
                 count: 1,
             });
@@ -1571,7 +1609,7 @@ fn handle_double_tap(
             let stack_index = pile_cards.cards.len() - drag.cards.len();
             if let Some(bottom_card) = pile_cards.cards.get(stack_index)
                 && let Some((dest, count)) =
-                    best_tableau_destination_for_stack(bottom_card, pile, &game.0, drag.cards.len())
+                    best_tableau_destination_for_stack(bottom_card, tapped_pile, &game.0, drag.cards.len())
             {
                 for (entity, ce, mut sprite) in card_sprites.iter_mut() {
                     if drag.cards.contains(&ce.card_id) {
@@ -1582,7 +1620,7 @@ fn handle_double_tap(
                     }
                 }
                 moves.write(MoveRequestEvent {
-                    from: pile.clone(),
+                    from: tapped_pile.clone(),
                     to: dest,
                     count,
                 });
@@ -1591,8 +1629,8 @@ fn handle_double_tap(
         }
 
         rejected.write(MoveRejectedEvent {
-            from: pile.clone(),
-            to: pile.clone(),
+            from: tapped_pile.clone(),
+            to: tapped_pile.clone(),
             count: drag.cards.len(),
         });
     }