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/onboarding_plugin.rs

@@ -59,7 +59,7 @@ fn dismiss_on_any_input(
     path: Option<Res<SettingsStoragePath>>,
     screens: Query<Entity, With<OnboardingScreen>>,
 ) {
-    let Ok(entity) = screens.get_single() else {
+    let Ok(entity) = screens.single() else {
         return;
     };
     let pressed = keys.get_just_pressed().next().is_some()
@@ -67,7 +67,7 @@ fn dismiss_on_any_input(
     if !pressed {
         return;
     }
-    commands.entity(entity).despawn_recursive();
+    commands.entity(entity).despawn();
     settings.0.first_run_complete = true;
     persist(path.as_deref().map(|p| &p.0), &settings.0);
 }