feat(maps): add Acheron, Debenter, Uruk, Ferea (maps 83-86)

Same pattern as Arkania: terrain resources Terrain84-87.att, map
initializer classes, registration, and update-plugin (v97) that
creates each map + spawn gate + /move warp AND assigns it to the
game server configuration so it is hosted. Also fix the Arkania
update-plugin to assign the game server config (was missing).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/Persistence/Initialization/Updates/AddArkaniaMapUpdateSeason6.cs

@@ -41,20 +41,31 @@ public class AddArkaniaMapUpdateSeason6 : UpdatePlugInBase
     public override DateTime CreatedAt => new(2026, 07, 19, 12, 0, 0, DateTimeKind.Utc);
 
     /// <inheritdoc />
-    protected override ValueTask ApplyAsync(IContext context, GameConfiguration gameConfiguration)
+    protected override async ValueTask ApplyAsync(IContext context, GameConfiguration gameConfiguration)
     {
-        // Idempotency guard: skip if Arkania (83) already exists.
+        // Idempotency guard: skip if Arkania (82) already exists.
         if (gameConfiguration.Maps.Any(m => m.Number == Arkania.Number))
         {
-            return default;
+            return;
         }
 
         var initializer = new Arkania(context, gameConfiguration);
-        initializer.Initialize();      // creates map 83 + loads terrain from Terrain84.att
+        initializer.Initialize();      // creates map 82 + loads terrain from Terrain83.att
         initializer.SetSafezoneMap();
 
         var arkania = gameConfiguration.Maps.First(m => m.Number == Arkania.Number);
 
+        // Host the map on every game server configuration (fresh seeds do this
+        // automatically, but existing databases need it added explicitly).
+        var serverConfigs = await context.GetAsync<GameServerConfiguration>().ConfigureAwait(false);
+        foreach (var serverConfig in serverConfigs)
+        {
+            if (serverConfig.Maps.All(m => m.Number != Arkania.Number))
+            {
+                serverConfig.Maps.Add(arkania);
+            }
+        }
+
         // Spawn gate on a walkable tile (center of the map; attr 0x00, verified walkable).
         var spawnGate = context.CreateNew<ExitGate>();
         arkania.ExitGates.Add(spawnGate);
@@ -76,7 +87,5 @@ public class AddArkaniaMapUpdateSeason6 : UpdatePlugInBase
             warp.LevelRequirement = 10;
             warp.Gate = spawnGate;
         }
-
-        return default;
     }
 }