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.Models/Auth/LoginResponse.cs

@@ -0,0 +1,39 @@
+using System.Text.Json.Serialization;
+
+namespace DorkNet.Models.Auth;
+
+/// <summary>
+/// Login.LoginResponse — dump.cs:578473 (private nested class),
+/// Deserialize at RVA 0x1447D10.
+///
+/// Verified by disassembly: this is a standard OAuth 2.0 RFC 6749
+/// password-grant token response. The Deserialize body has two branches:
+///
+///   error = dict["error"];
+///   if (string.IsNullOrEmpty(error)) {
+///       this.AccessToken  = dict["access_token"];
+///       this.RefreshToken = dict["refresh_token"];
+///   } else {
+///       this.ErrorDescription = dict["error_description"];
+///   }
+///
+/// Returned by api/platformlogin/v5 (the 2020 build's login endpoint)
+/// and api/platformlogin/refresh.
+///
+/// All four keys are snake_case, NOT PascalCase. This is the standard
+/// OAuth response format — Rec Room conforms to RFC 6749 here.
+/// </summary>
+public class LoginResponse
+{
+    [JsonPropertyName("error")]
+    public string? Error { get; set; }
+
+    [JsonPropertyName("error_description")]
+    public string? ErrorDescription { get; set; }
+
+    [JsonPropertyName("access_token")]
+    public string AccessToken { get; set; } = string.Empty;
+
+    [JsonPropertyName("refresh_token")]
+    public string RefreshToken { get; set; } = string.Empty;
+}