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/Configuration/PluginConfiguration.cs

@@ -0,0 +1,44 @@
+using MediaBrowser.Model.Plugins;
+
+namespace Jellyfin.Plugin.ShareLinks.Configuration;
+
+/// <summary>
+/// Plugin configuration persisted by Jellyfin.
+/// </summary>
+public class PluginConfiguration : BasePluginConfiguration
+{
+    /// <summary>Gets or sets a value indicating whether the plugin is enabled.</summary>
+    public bool Enabled { get; set; } = true;
+
+    /// <summary>Gets or sets the default share expiry in hours.</summary>
+    public int DefaultExpiryHours { get; set; } = 24;
+
+    /// <summary>Gets or sets the maximum allowed share expiry in hours.</summary>
+    public int MaxExpiryHours { get; set; } = 720;
+
+    /// <summary>
+    /// Gets or sets an override for the public base URL used when building
+    /// absolute share links. Empty means "derive from the incoming request".
+    /// </summary>
+    public string PublicBaseUrlOverride { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the prefix used when creating guest user names.
+    /// </summary>
+    public string GuestUsernamePrefix { get; set; } = "share-";
+
+    /// <summary>Gets or sets a value indicating whether shares may transcode.</summary>
+    public bool AllowTranscoding { get; set; } = true;
+
+    /// <summary>Gets or sets a value indicating whether shares may remux.</summary>
+    public bool AllowRemuxing { get; set; } = true;
+
+    /// <summary>Gets or sets the cleanup interval, in minutes.</summary>
+    public int CleanupIntervalMinutes { get; set; } = 60;
+
+    /// <summary>Gets or sets a value indicating whether links default to one use.</summary>
+    public bool OneUseDefault { get; set; } = true;
+
+    /// <summary>Gets or sets a value indicating whether guest-mode lockdown is enabled.</summary>
+    public bool GuestModeLockdownEnabled { get; set; } = true;
+}