fix(engine): snap cards directly on window resize

on_window_resized was firing StateChangedEvent on every WindowResized
event. That ran sync_cards_on_change → update_card_entity, which
inserts a CardAnim slide tween for every card whose target moves >1
unit. During a corner drag the resize fires every frame, retargeting
the slide each time from the cards' current mid-tween positions, so
cards never reach steady state — the visible "snap back and forth"
jitter reported during the 2026-04-29 smoke test.

Replace the StateChangedEvent emit with a direct snap path:

- Add LayoutSystem::UpdateOnResize SystemSet in layout.rs so cross-
  plugin ordering is explicit (Bevy's automatic conflict-based order
  only forces non-parallel execution, not a particular order).
- table_plugin::on_window_resized: drop the StateChangedEvent emit;
  mark the system in_set(LayoutSystem::UpdateOnResize). It already
  snaps backgrounds and pile markers directly, so this aligns cards
  with the same instant-snap policy.
- card_plugin: new snap_cards_on_window_resize system listens for
  WindowResized, runs .after(LayoutSystem::UpdateOnResize), writes
  fresh transforms via the existing card_positions() helper, and
  removes any in-flight CardAnim. It also reapplies the stock-empty
  indicator so the "↺" label's font_size (derived from
  layout.card_size.x) still rescales on resize.

Other StateChangedEvent listeners — start_settle_anim,
detect_auto_complete, clear_selection_on_state_change, check_no_moves,
reset_hint_cycle_on_state_change, clear_right_click_highlights — no
longer fire spuriously on resize. They should not fire on a layout
change anyway; that was a pre-existing minor bug masked by the
jitter.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

solitaire_engine/src/layout.rs

@@ -6,10 +6,22 @@
 use std::collections::HashMap;
 
 use bevy::math::Vec2;
-use bevy::prelude::Resource;
+use bevy::prelude::{Resource, SystemSet};
 use solitaire_core::card::Suit;
 use solitaire_core::pile::PileType;
 
+/// Schedule labels for layout-related systems so cross-plugin ordering is
+/// explicit instead of relying on Bevy's automatic resource-conflict ordering
+/// (which only forces non-parallel execution, not a particular order).
+#[derive(SystemSet, Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum LayoutSystem {
+    /// The system that updates [`LayoutResource`], the table background, and
+    /// pile markers in response to a `WindowResized` event. Card-snap systems
+    /// (in `card_plugin`) run `.after(LayoutSystem::UpdateOnResize)` so they
+    /// see the fresh layout.
+    UpdateOnResize,
+}
+
 /// Minimum supported window dimensions. Layout is still computed below this
 /// size but cards will be small.
 pub const MIN_WINDOW: Vec2 = Vec2::new(800.0, 600.0);