fix(engine,server): safe area clamp, analytics batch, achievement save order, daily rollover, replay validation, leaderboard opt-in (#56, #60, #61, #62, #66, #68)

- #66: Clamp safe-area insets to 25% of window height with warn!() on excess
- #68: Move fire_flush outside per-event loop in analytics (batch flush once)
- #56: Persist progress before marking reward_granted to prevent XP loss on crash
- #60: Add DateRolloverTimer + check_date_rollover system for midnight seed refresh
- #62: Add validate_header() in replay upload with mode/draw_mode allowlists
- #61: Restore two-query leaderboard opt-in check (SELECT then UPDATE); original
       queries already in .sqlx cache; EXISTS variant would require sqlx prepare

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

solitaire_engine/src/difficulty_plugin.rs

@@ -74,10 +74,7 @@ impl Plugin for DifficultyPlugin {
         app.init_resource::<DifficultyIndexResource>()
             .add_message::<StartDifficultyRequestEvent>()
             .add_message::<NewGameRequestEvent>()
-            .add_systems(
-                Update,
-                handle_difficulty_request.before(GameMutation),
-            );
+            .add_systems(Update, handle_difficulty_request.before(GameMutation));
     }
 }
 
@@ -210,7 +207,10 @@ mod tests {
 
         let events = drain_new_game_events(&mut app);
         assert_eq!(events.len(), 1);
-        assert!(events[0].seed.is_some(), "Random should always produce Some(seed)");
+        assert!(
+            events[0].seed.is_some(),
+            "Random should always produce Some(seed)"
+        );
         assert_eq!(
             events[0].mode,
             Some(GameMode::Difficulty(DifficultyLevel::Random))