feat(android): long-press opens radial menu as right-click alternative

Touch screens have no right mouse button, so right-click radial was
inaccessible on Android. New system radial_open_on_long_press counts
up while a touch is held on a face-up card without crossing the drag
threshold; after 0.5 s it transitions RightClickRadialState to Active,
which the existing visual overlay and destination-ring infrastructure
then renders unchanged.

Three supporting changes to wire up the touch-driven confirm path:

- radial_track_cursor: falls back to the first active Touches position
  when cursor_world returns None, so the hover ring tracks a sliding
  held finger on Android.

- radial_handle_release_or_cancel: confirms on Touches::iter_just_released
  (finger lift) in addition to right-mouse release. Cancels on
  Touches::iter_just_canceled. No new event reader — uses the Touches
  resource which is already in scope after the track_cursor addition.

- handle_double_tap: skips when the radial is active. Guards the
  narrow edge case where the finger lifts on the exact same frame
  as the 0.5 s long-press threshold fires; prevents a spurious
  double-tap move from racing with the radial confirm.

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

solitaire_engine/src/input_plugin.rs

@@ -34,6 +34,7 @@ use solitaire_core::rules::{can_place_on_foundation, can_place_on_tableau};
 use crate::card_animation::tuning::AnimationTuning;
 use crate::card_animation::{CardAnimation, MotionCurve};
 use crate::card_plugin::{CardEntity, HintHighlight, HintHighlightTimer, STACK_FAN_FRAC};
+use crate::radial_menu::RightClickRadialState;
 use crate::ui_theme::{MOTION_DRAG_REJECT_SECS, STATE_SUCCESS, STATE_WARNING};
 use solitaire_core::game_state::DrawMode;
 use crate::challenge_plugin::CHALLENGE_UNLOCK_LEVEL;
@@ -1413,6 +1414,7 @@ fn handle_double_click(
 fn handle_double_tap(
     mut touch_events: MessageReader<TouchInput>,
     paused: Option<Res<PausedResource>>,
+    radial: Option<Res<RightClickRadialState>>,
     time: Res<Time>,
     drag: Res<DragState>,
     game: Res<GameStateResource>,
@@ -1425,6 +1427,11 @@ fn handle_double_tap(
     if paused.is_some_and(|p| p.0) {
         return;
     }
+    // Long-press opened the radial in this frame — let radial_handle_release_or_cancel
+    // own the finger-lift event instead.
+    if radial.is_some_and(|r| r.is_active()) {
+        return;
+    }
 
     // Only active when a touch is tracked and hasn't crossed the drag threshold.
     let Some(active_id) = drag.active_touch_id else { return };