refactor(engine): first ambiguity burn-down batch — 302 → 198 pairs

Two structural fixes from the #143 backlog:

- Game-state ordering spine: the three pre-mutation GameStateResource
  writers (tick_elapsed_time, sync_settings_to_game,
  handle_restore_prompt) are now a deterministic chain before
  GameMutation, and the remaining unordered readers
  (update_selection_hud, handle_hint_button, tick_hint_highlight,
  handle_right_click, snap_cards_on_window_resize,
  sync_pile_marker_visibility, auto_save_game_state) are ordered after
  it. Readers now see the current frame's moves deterministically
  instead of racing the mutators.

- NewGameRequestWriters set: every in-cluster writer of
  NewGameRequestEvent (buttons, modals, mode picker, seed poller,
  restore prompt) is registered in a shared set marked ambiguous with
  itself — writer-vs-writer append order is meaningless since consumers
  drain the whole queue. Out-of-cluster writers (home, challenge,
  time-attack, win-summary, play-by-seed, difficulty, stats plugins)
  can join the set when the test cluster grows.

AMBIGUITY_BASELINE ratchets 302 → 198. Remaining backlog is dominated
by the Sprite (72) / Transform (48) visual-domain cluster, which needs
per-domain set architecture — next batch.

Refs #143

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

solitaire_engine/src/card_plugin/mod.rs

@@ -570,8 +570,8 @@ impl Plugin for CardPlugin {
                     tick_flip_anim,
                     update_drag_shadow,
                     update_card_shadows_on_drag.after(sync_cards_on_change),
-                    tick_hint_highlight,
-                    handle_right_click,
+                    tick_hint_highlight.after(GameMutation),
+                    handle_right_click.after(GameMutation),
                     tick_right_click_highlights,
                     clear_right_click_highlights_on_state_change.after(GameMutation),
                     clear_right_click_highlights_on_pause,
@@ -580,7 +580,9 @@ impl Plugin for CardPlugin {
                         .after(GameMutation)
                         .run_if(resource_changed::<GameStateResource>),
                     collect_resize_events.after(LayoutSystem::UpdateOnResize),
-                    snap_cards_on_window_resize.after(collect_resize_events),
+                    snap_cards_on_window_resize
+                        .after(collect_resize_events)
+                        .after(GameMutation),
                 ),
             );