chore: add .editorconfig and consistent formatting for backend projects

Adds an `.editorconfig` file with C# and project-specific conventions. Applies consistent indentation and formatting across backend handlers, runtime models, and AI services.

apps/backend/Universe/Api/GetWorldHealthHandler.cs

@@ -4,20 +4,20 @@ namespace SpaceGame.Api.Universe.Api;
 
 public sealed class GetWorldHealthHandler(WorldService worldService) : EndpointWithoutRequest
 {
-  public override void Configure()
-  {
-    Get("/api/world/health");
-    AllowAnonymous();
-  }
-
-  public override Task HandleAsync(CancellationToken cancellationToken)
-  {
-    var status = worldService.GetStatus();
-    return SendOkAsync(new
+    public override void Configure()
     {
-      ok = true,
-      sequence = status.Sequence,
-      generatedAtUtc = status.GeneratedAtUtc,
-    }, cancellationToken);
-  }
+        Get("/api/world/health");
+        AllowAnonymous();
+    }
+
+    public override Task HandleAsync(CancellationToken cancellationToken)
+    {
+        var status = worldService.GetStatus();
+        return SendOkAsync(new
+        {
+            ok = true,
+            sequence = status.Sequence,
+            generatedAtUtc = status.GeneratedAtUtc,
+        }, cancellationToken);
+    }
 }