feat(CS): weekly auto-schedule (day-of-week + UTC time), persisted, /csschedule GM cmd

The siege can now auto-open registration on scheduled days/time instead of only
manual /csphase. Schedule is context-owned state (like owner), persisted across
restarts via the same config-JSON path. New GM command /csschedule sets/views/clears
it (e.g. /csschedule Sunday 20:00, UTC). +2 unit tests (11 total).

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

src/GameLogic/PlugIns/ChatCommands/CastleSiegeScheduleChatCommandPlugIn.cs

@@ -0,0 +1,101 @@
+// <copyright file="CastleSiegeScheduleChatCommandPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic.PlugIns.ChatCommands;
+
+using System.Globalization;
+using System.Linq;
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.CastleSiege;
+using MUnique.OpenMU.GameLogic.PlugIns.PeriodicTasks;
+using MUnique.OpenMU.GameLogic.Views;
+using MUnique.OpenMU.Interfaces;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// Sets the Castle Siege weekly auto-schedule. GM only. Times are UTC.
+/// Usage: <c>/csschedule</c> (show) | <c>/csschedule Sunday 20:00</c> | <c>/csschedule Sunday,Wednesday 20:00</c> | <c>/csschedule clear</c>.
+/// </summary>
+[Guid("A1B2C3D4-0006-4E5F-9A0B-CA5710000006")]
+[PlugIn]
+[Display(Name = "Castle Siege Schedule", Description = "GM command: /csschedule [<days> <HH:mm UTC> | clear]")]
+[ChatCommandHelp(Command, CharacterStatus.GameMaster)]
+public class CastleSiegeScheduleChatCommandPlugIn : IChatCommandPlugIn
+{
+    private const string Command = "/csschedule";
+
+    /// <inheritdoc />
+    public string Key => Command;
+
+    /// <inheritdoc/>
+    public CharacterStatus MinCharacterStatusRequirement => CharacterStatus.GameMaster;
+
+    /// <inheritdoc />
+    public async ValueTask HandleCommandAsync(Player player, string command)
+    {
+        var context = CastleSiegeEventPlugIn.TryGetContext(player.GameContext);
+        if (context is null)
+        {
+            await ShowAsync(player, "Castle Siege plugin not active.").ConfigureAwait(false);
+            return;
+        }
+
+        var parts = command.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+
+        // "/csschedule" -> show current schedule.
+        if (parts.Length == 1)
+        {
+            await ShowAsync(player, Describe(context)).ConfigureAwait(false);
+            return;
+        }
+
+        // "/csschedule clear" -> disable auto-start.
+        if (parts.Length == 2 && string.Equals(parts[1], "clear", StringComparison.OrdinalIgnoreCase))
+        {
+            context.SetSchedule(Array.Empty<DayOfWeek>(), null);
+            await ShowAsync(player, "Castle Siege auto-schedule cleared (manual start only).").ConfigureAwait(false);
+            return;
+        }
+
+        if (parts.Length < 3)
+        {
+            await ShowAsync(player, "Usage: /csschedule <day[,day...]> <HH:mm UTC>  |  /csschedule clear").ConfigureAwait(false);
+            return;
+        }
+
+        var days = new List<DayOfWeek>();
+        foreach (var token in parts[1].Split(',', StringSplitOptions.RemoveEmptyEntries))
+        {
+            if (!Enum.TryParse<DayOfWeek>(token, true, out var day))
+            {
+                await ShowAsync(player, $"Unknown day '{token}'. Use e.g. Sunday, Monday, Tuesday...").ConfigureAwait(false);
+                return;
+            }
+
+            days.Add(day);
+        }
+
+        if (!TimeOnly.TryParse(parts[2], CultureInfo.InvariantCulture, out var time))
+        {
+            await ShowAsync(player, $"Invalid time '{parts[2]}'. Use 24h HH:mm (UTC).").ConfigureAwait(false);
+            return;
+        }
+
+        context.SetSchedule(days, time);
+        await ShowAsync(player, $"{Describe(context)} Server UTC now: {DateTime.UtcNow:ddd HH:mm}.").ConfigureAwait(false);
+    }
+
+    private static string Describe(CastleSiegeContext context)
+    {
+        if (context.ScheduleTime is not { } time || context.ScheduleDays.Count == 0)
+        {
+            return "Castle Siege auto-schedule: (none). Set with /csschedule <days> <HH:mm UTC>.";
+        }
+
+        return $"Castle Siege auto-schedule: {string.Join(",", context.ScheduleDays)} at {time:HH:mm} UTC.";
+    }
+
+    private static ValueTask ShowAsync(Player player, string text)
+        => player.InvokeViewPlugInAsync<IShowMessagePlugIn>(p => p.ShowMessageAsync(text, MessageType.BlueNormal));
+}

src/GameLogic/PlugIns/PeriodicTasks/CastleSiegeEventPlugIn.cs

@@ -75,7 +75,7 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
 
             // Restore state persisted before the last restart (owner/phase/registrations) BEFORE subscribing,
             // so restoring doesn't announce phases or re-spawn defenses.
-            created.RestoreState(config.PersistedOwnerGuildName, config.PersistedPhase, config.PersistedPhaseStartedUtc, config.PersistedRegisteredGuilds);
+            created.RestoreState(config.PersistedOwnerGuildName, config.PersistedPhase, config.PersistedPhaseStartedUtc, config.PersistedRegisteredGuilds, config.PersistedScheduleDays, config.PersistedScheduleTime);
 
             // Announce phase changes to the whole server and, when the siege begins, warp registered members.
             created.PhaseChanged += phase => _ = OnPhaseChangedAsync(gc, created, phase);
@@ -150,6 +150,8 @@ public sealed class CastleSiegeEventPlugIn : IPeriodicTaskPlugIn, ISupportCustom
             config.PersistedPhase = context.Phase;
             config.PersistedPhaseStartedUtc = context.PhaseStartedUtc;
             config.PersistedRegisteredGuilds = context.RegisteredGuilds.ToList();
+            config.PersistedScheduleDays = context.ScheduleDays.ToList();
+            config.PersistedScheduleTime = context.ScheduleTime;
 
             // Find our plugin-configuration row via the in-memory config graph to get its id.
             var pluginTypeId = typeof(CastleSiegeEventPlugIn).GUID;