ShareLinks plugin: guest share links for Jellyfin

Includes fix for redemption failing with DbUpdateConcurrencyException:
change the guest password before applying the user policy, since
UpdatePolicyAsync bumps the user's EF concurrency token and a stale
instance then breaks ChangePassword.

Jellyfin.Plugin.ShareLinks/Tasks/CleanupShareLinksScheduledTask.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Plugin.ShareLinks.Services;
+using MediaBrowser.Model.Tasks;
+
+namespace Jellyfin.Plugin.ShareLinks.Tasks;
+
+/// <summary>
+/// Scheduled cleanup shell for later link-expiry and guest-account teardown work.
+/// </summary>
+public sealed class CleanupShareLinksScheduledTask : IScheduledTask, IConfigurableScheduledTask
+{
+    private readonly IShareLinkCleanupService _cleanupService;
+
+    /// <summary>Initializes a new instance of the <see cref="CleanupShareLinksScheduledTask"/> class.</summary>
+    public CleanupShareLinksScheduledTask(IShareLinkCleanupService cleanupService)
+    {
+        _cleanupService = cleanupService;
+    }
+
+    /// <inheritdoc />
+    public string Name => "Clean up ShareLinks";
+
+    /// <inheritdoc />
+    public string Key => "ShareLinksCleanup";
+
+    /// <inheritdoc />
+    public string Description => "Removes expired share links and performs future guest-account cleanup.";
+
+    /// <inheritdoc />
+    public string Category => "ShareLinks";
+
+    /// <inheritdoc />
+    public bool IsHidden => false;
+
+    /// <inheritdoc />
+    public bool IsEnabled => true;
+
+    /// <inheritdoc />
+    public bool IsLogged => true;
+
+    /// <inheritdoc />
+    public async Task ExecuteAsync(IProgress<double> progress, CancellationToken cancellationToken)
+    {
+        _ = progress;
+        await _cleanupService.CleanupAsync(cancellationToken).ConfigureAwait(false);
+    }
+
+    /// <inheritdoc />
+    public IEnumerable<TaskTriggerInfo> GetDefaultTriggers()
+    {
+        yield return new TaskTriggerInfo
+        {
+            Type = TaskTriggerInfoType.DailyTrigger,
+            TimeOfDayTicks = TimeSpan.FromHours(4).Ticks,
+        };
+    }
+}