Import march-2020-03-10 from private repo (scrubbed 2026-05-27)

Targets Rec Room 2020.03.10 client (also serves 2020.03.06).

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 dorknet-clientpatch-{key}.zip
  for v1-march-* Release uploads.
- .github/workflows/release.yml — on tag push publishes both
  dorknet-server-march_2020_03_10-win-x64.zip and
  dorknet-clientpatch-march_2020_03_10.zip as Release assets.

Same scrub rules as december; tools/build-patcher-zip.ps1 added to
the maintainer-side allow-list so it survives.

DorkNet.Server/Data/Entities/ServerSettingsEntity.cs

@@ -0,0 +1,26 @@
+namespace DorkNet.Server.Data.Entities;
+
+/// <summary>
+/// Single-row table holding server-wide runtime toggles that admins can
+/// flip from the SPA without a redeploy. Modelled after
+/// <see cref="CommunityBoardEntity"/>: <see cref="Id"/> is pinned to 1
+/// so EF Core has a key to track changes against, and reads/writes
+/// touch one row.
+///
+/// Add new boolean (or scalar) columns directly to this entity as more
+/// toggles appear — keeping them strongly typed beats a generic
+/// key/value table for the dozen-or-so global switches we'll ever have.
+/// </summary>
+public class ServerSettingsEntity
+{
+    public int Id { get; set; } = 1;
+
+    /// <summary>When true, the watch's account-creation endpoints
+    /// (<c>POST /account/create</c> and <c>POST /api/account/v1/create</c>)
+    /// short-circuit with <c>Success=false</c> and the watch surfaces
+    /// the error to the player. Existing logins are unaffected; only
+    /// brand-new account requests are blocked.</summary>
+    public bool SignupsDisabled { get; set; }
+
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}