refactor(engine): ambiguity burn-down batch 4 — zero ambiguities, gate enforced

Clears the final 47 pairs and turns the ratchet into a hard gate
(AMBIGUITY_BASELINE = 0, assert_eq):

- HudButtons: the 14 HUD button/popover handlers run as one chain,
  before ui_focus::FocusKeys — Esc/keyboard consumption order is now
  defined (restore prompt → buttons/popovers → focus navigation →
  settings toggle) instead of scheduler-dependent.
- HUD text updaters (update_hud, update_selection_hud,
  update_won_previously) chained, in UiTextFx, after the new
  AutoComplete set (update_hud reads AutoCompleteState).
- restore_hud_on_modal → apply_hud_visibility chained before
  UpdateOnResize: HudVisibility writes, application, and the layout
  read happen in a fixed order.
- New writer sets UndoRequestWriters / InfoToastWriters (same
  self-ambiguous pattern as NewGameRequestWriters).
- Logic-before-paint: check_no_moves and the AutoComplete chain order
  before BoardVisuals; SettingsMutation after UpdateOnResize.
- MarkerVisuals set wraps the table painter chain; chrome fx declare
  disjointness from it.
- update_hud_typography after BoardVisuals; avatar/settings-toggle
  interaction handlers declared disjoint from HudButtons.

302 → 198 → 171 → 47 → 0 in four batches, one day. New systems now
fail CI unless they declare their ordering or their disjointness.

Closes #143

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

solitaire_engine/src/ui_focus.rs

@@ -117,6 +117,13 @@ pub struct FocusedButton(pub Option<Entity>);
 /// gains keyboard navigation without per-plugin wiring.
 pub struct UiFocusPlugin;
 
+/// Set on [`handle_focus_keys`], the focus-ring keyboard navigator. It runs
+/// AFTER every app-level keyboard consumer (HUD buttons/popovers, restore
+/// prompt, settings toggle) so Esc/Tab consumption order is defined instead
+/// of scheduler-dependent (#143).
+#[derive(bevy::ecs::schedule::SystemSet, Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FocusKeys;
+
 impl Plugin for UiFocusPlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<FocusedButton>()
@@ -147,8 +154,14 @@ impl Plugin for UiFocusPlugin {
                 (
                     sync_focus_on_mouse_click,
                     clear_hud_focus_on_unhover,
-                    handle_focus_keys,
-                    update_focus_overlay,
+                    handle_focus_keys
+                        .in_set(FocusKeys)
+                        .after(crate::game_plugin::GameMutation),
+                    update_focus_overlay
+                        .in_set(crate::ui_theme::UiTextFx)
+                        .ambiguous_with(crate::ui_theme::UiTextFx)
+                        .ambiguous_with(crate::card_plugin::BoardVisuals)
+                        .ambiguous_with(crate::table_plugin::MarkerVisuals),
                     pulse_focus_overlay
                         .after(crate::settings_plugin::SettingsMutation)
                         .in_set(crate::ui_theme::UiTextFx)