Add event-driven state sync with ETag optimization

Endpoints/StateWorkflowService.cs

@@ -9,9 +9,34 @@ internal sealed class StateWorkflowService(AppDbContext db)
 {
     public async Task<ServiceResult<StateSummaryResponse>> GetStateAsync(Player player)
     {
-        var state = await db.AppState.AsNoTracking().SingleAsync();
+        var state = await db.AppState
+            .AsNoTracking()
+            .Select(s => new
+            {
+                s.ResultsOpen,
+                s.UpdatedAt,
+                Players = db.Players.Count(),
+                Suggestions = db.Suggestions.Count(),
+                Votes = db.Votes.Count()
+            })
+            .SingleAsync();
+
         var phase = EndpointHelpers.GetCurrentPhase(player.CurrentPhase, state.ResultsOpen);
-        var summary = new StateSummaryResponse(phase, player.VotesFinal, player.HasJoker, state.ResultsOpen, state.UpdatedAt, await db.Players.CountAsync(), await db.Suggestions.CountAsync(), await db.Votes.CountAsync());
+        var summary = new StateSummaryResponse(
+            player.Id,
+            player.Username,
+            player.DisplayName,
+            player.IsAdmin,
+            player.IsOwner,
+            phase,
+            player.VotesFinal,
+            player.HasJoker,
+            state.ResultsOpen,
+            state.UpdatedAt,
+            state.Players,
+            state.Suggestions,
+            state.Votes
+        );
         return ServiceResult<StateSummaryResponse>.Success(summary);
     }