chore(deps): migrate to Bevy 0.16, axum 0.8, and other package updates

- Bump bevy 0.15 → 0.16; fixes all breaking API changes:
  ChildBuilder → ChildSpawnerCommands, Parent → ChildOf,
  despawn_descendants → despawn_related::<Children>(),
  despawn_recursive → despawn (now recursive by default),
  EventWriter::send → write, Query::{get_single,get_single_mut}
  → {single,single_mut}, ChildOf::get → parent()
- Bump axum 0.7 → 0.8; remove axum::async_trait from FromRequestParts
- Bump tower_governor 0.4 → 0.8; fix GovernorLayer::new() API
- Bump jsonwebtoken 9 → 10 with rust_crypto feature only
- Bump thiserror 1 → 2, dirs 5 → 6, bcrypt 0.15 → 0.19,
  reqwest 0.12 → 0.13 (rustls feature rename)
- Regenerate .sqlx offline cache for sqlx compile-time query checks

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

solitaire_engine/src/animation_plugin.rs

@@ -465,7 +465,7 @@ fn drive_toast_display(
         active.timer -= dt;
         if active.timer <= 0.0 {
             // Despawn the toast entity and clear the active slot.
-            commands.entity(entity).despawn_recursive();
+            commands.entity(entity).despawn();
             active.entity = None;
             active.timer = 0.0;
         }
@@ -532,7 +532,7 @@ fn tick_toasts(
     for (entity, mut timer) in &mut toasts {
         timer.0 -= dt;
         if timer.0 <= 0.0 {
-            commands.entity(entity).despawn_recursive();
+            commands.entity(entity).despawn();
         }
     }
 }