Import december-2020-12-18 from private repo (scrubbed 2026-05-27)

Targets Rec Room 2020.12.18 client.

Re-import after adding:
- DorkNet.ClientMod/dorknet-clientmod.json.template — config schema
  the launcher's manifest-driven patcher renders into UserData/.
- tools/build-patcher-zip.ps1 — produces the dorknet-clientpatch-{key}.zip
  Release asset the launcher fetches.
- .github/workflows/release.yml — auto-publishes both Release assets
  on v1-december-* tag push.

Scrubbed via maintainer-side scrub-for-public.ps1: same drop rules as
the prior import, plus build-patcher-zip.ps1 added to the tools/
allow-list so it survives the scrub.

DorkNet.Server/Data/Entities/PlayerSystemsEntities.cs

@@ -0,0 +1,66 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace DorkNet.Server.Data.Entities;
+
+/// <summary>
+/// One per (player, deviceId) — recorded on
+/// <c>POST /api/deviceid/v1/register</c>. Lets admins flag
+/// duplicate-account abuse: when a banned player creates a new
+/// account on the same device, the new account inherits the device
+/// ban automatically.
+/// </summary>
+public class PlayerDeviceEntity
+{
+    public long Id { get; set; }
+    public long PlayerId { get; set; }
+
+    [MaxLength(128)]
+    public string DeviceId { get; set; } = string.Empty;
+
+    [MaxLength(32)]
+    public string Platform { get; set; } = string.Empty;
+
+    public DateTime FirstSeen { get; set; } = DateTime.UtcNow;
+    public DateTime LastSeen { get; set; } = DateTime.UtcNow;
+
+    /// <summary>Set by admin tooling — if true, every account using
+    /// this device is auto-banned at login.</summary>
+    public bool IsBanned { get; set; } = false;
+}
+
+/// <summary>Per-player notification preferences. iOS-style toggle
+/// page; Android / Quest just persist the same shape.</summary>
+public class NotificationPrefsEntity
+{
+    public long Id { get; set; }
+    public long PlayerId { get; set; }
+
+    [MaxLength(32)]
+    public string Platform { get; set; } = string.Empty;
+
+    public bool AllowAll { get; set; } = true;
+    public bool AllowFriendRequest { get; set; } = true;
+    public bool AllowMessage { get; set; } = true;
+    public bool AllowEventInvite { get; set; } = true;
+    public bool AllowAnnouncements { get; set; } = true;
+
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}
+
+/// <summary>Sticky cohort assignment — one row per (player, cohort
+/// key). Created on first hit to <c>GET /api/cohort/v1/{key}</c> with
+/// a randomly selected variant; remains stable for the lifetime of
+/// the player so A/B tests don't flicker between sessions.</summary>
+public class CohortAssignmentEntity
+{
+    public long Id { get; set; }
+    public long PlayerId { get; set; }
+
+    [MaxLength(64)]
+    public string CohortKey { get; set; } = string.Empty;
+
+    [MaxLength(32)]
+    public string Variant { get; set; } = string.Empty;
+
+    public DateTime AssignedAt { get; set; } = DateTime.UtcNow;
+}