Practice/deck editing mostly there

SVSim.EmulatedEntrypoint/Services/FacepunchSteamServer.cs

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+using Steamworks;
+
+namespace SVSim.EmulatedEntrypoint.Services;
+
+/// <summary>
+/// Production <see cref="ISteamServer"/> backed by Facepunch.Steamworks 2.3.3.
+/// Initialization is process-global; registering this as a singleton is required.
+/// </summary>
+public sealed class FacepunchSteamServer : ISteamServer
+{
+    private readonly object _initLock = new();
+    private bool _initialized;
+
+    public void Initialize(int appId)
+    {
+        if (_initialized) return;
+        lock (_initLock)
+        {
+            if (_initialized) return;
+            SteamServer.Init(appId, new SteamServerInit
+            {
+                GamePort = default,
+                QueryPort = default,
+            });
+            _initialized = true;
+        }
+    }
+
+    public bool BeginAuthSession(byte[] ticket, ulong steamId) =>
+        SteamServer.BeginAuthSession(ticket, new SteamId { Value = steamId });
+
+    public void EndSession(ulong steamId) =>
+        SteamServer.EndSession(new SteamId { Value = steamId });
+
+    public void Shutdown()
+    {
+        if (!_initialized) return;
+        SteamServer.Shutdown();
+        _initialized = false;
+    }
+}