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/AddImportedMapsUpdateSeason6.cs

@@ -0,0 +1,100 @@
+// <copyright file="AddImportedMapsUpdateSeason6.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.Persistence.Initialization.Updates;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.DataModel.Configuration;
+using MUnique.OpenMU.Persistence.Initialization.VersionSeasonSix.Maps;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// Adds the four imported maps Acheron (83), Debenter (84), Uruk (85) and Ferea (86):
+/// the map definitions with their terrain, a spawn gate and a /move warp each, and
+/// assigns each to the game server configuration so it is hosted and its spawns run.
+/// Monsters and NPCs are added afterwards via the admin panel.
+/// </summary>
+[PlugIn]
+[Display(Name = PlugInName, Description = PlugInDescription)]
+[Guid("3D9C1B72-7C3F-4E8B-AF14-E29D47A8B012")]
+public class AddImportedMapsUpdateSeason6 : UpdatePlugInBase
+{
+    internal const string PlugInName = "Add imported maps (Acheron, Debenter, Uruk, Ferea)";
+    internal const string PlugInDescription = "Adds maps 83-86 (Acheron, Debenter, Uruk, Ferea) with terrain, spawn gate and /move warp, hosted by the game server. Monsters/NPCs are added via the admin panel.";
+
+    /// <inheritdoc />
+    public override UpdateVersion Version => UpdateVersion.AddImportedMapsSeason6;
+
+    /// <inheritdoc />
+    public override string DataInitializationKey => VersionSeasonSix.DataInitialization.Id;
+
+    /// <inheritdoc />
+    public override string Name => PlugInName;
+
+    /// <inheritdoc />
+    public override string Description => PlugInDescription;
+
+    /// <inheritdoc />
+    public override bool IsMandatory => true;
+
+    /// <inheritdoc />
+    public override DateTime CreatedAt => new(2026, 07, 19, 15, 0, 0, DateTimeKind.Utc);
+
+    /// <inheritdoc />
+    protected override async ValueTask ApplyAsync(IContext context, GameConfiguration gameConfiguration)
+    {
+        var serverConfigs = (await context.GetAsync<GameServerConfiguration>().ConfigureAwait(false)).ToList();
+
+        AddMap(context, gameConfiguration, serverConfigs, new Acheron(context, gameConfiguration), Acheron.Number, Acheron.Name, 84, 127, 126);
+        AddMap(context, gameConfiguration, serverConfigs, new Debenter(context, gameConfiguration), Debenter.Number, Debenter.Name, 85, 132, 105);
+        AddMap(context, gameConfiguration, serverConfigs, new Uruk(context, gameConfiguration), Uruk.Number, Uruk.Name, 86, 128, 128);
+        AddMap(context, gameConfiguration, serverConfigs, new Ferea(context, gameConfiguration), Ferea.Number, Ferea.Name, 87, 128, 128);
+    }
+
+    private static void AddMap(IContext context, GameConfiguration gameConfiguration, IList<GameServerConfiguration> serverConfigs, IMapInitializer initializer, byte number, string name, short warpIndex, byte x, byte y)
+    {
+        // Idempotency guard: skip if the map already exists.
+        if (gameConfiguration.Maps.Any(m => m.Number == number))
+        {
+            return;
+        }
+
+        initializer.Initialize();      // creates the map + loads terrain from Terrain{number+1}.att
+        initializer.SetSafezoneMap();
+
+        var map = gameConfiguration.Maps.First(m => m.Number == number);
+
+        // Spawn gate on a walkable tile.
+        var spawnGate = context.CreateNew<ExitGate>();
+        map.ExitGates.Add(spawnGate);
+        spawnGate.Map = map;
+        spawnGate.X1 = x;
+        spawnGate.Y1 = y;
+        spawnGate.X2 = x;
+        spawnGate.Y2 = y;
+        spawnGate.IsSpawnGate = true;
+
+        // /move warp entry.
+        if (gameConfiguration.WarpList.All(w => w.Name != name))
+        {
+            var warp = context.CreateNew<WarpInfo>();
+            gameConfiguration.WarpList.Add(warp);
+            warp.Index = warpIndex;
+            warp.Name = name;
+            warp.Costs = 5000;
+            warp.LevelRequirement = 10;
+            warp.Gate = spawnGate;
+        }
+
+        // Host the map on every game server configuration (fresh seeds do this
+        // automatically, but existing databases need it added explicitly).
+        foreach (var serverConfig in serverConfigs)
+        {
+            if (serverConfig.Maps.All(m => m.Number != number))
+            {
+                serverConfig.Maps.Add(map);
+            }
+        }
+    }
+}