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/Services/ServerSettingsService.cs

@@ -0,0 +1,58 @@
+using DorkNet.Server.Data;
+using DorkNet.Server.Data.Entities;
+using Microsoft.EntityFrameworkCore;
+
+namespace DorkNet.Server.Services;
+
+/// <summary>
+/// Single-row settings store. Same Postgres-backed pattern as
+/// <see cref="CommunityBoardService"/>: every read is one SELECT,
+/// every write is one UPDATE/INSERT, and the row is visible to every
+/// replica immediately so admin toggles propagate without a cache
+/// invalidation dance.
+///
+/// Scoped (not singleton) because it holds a DbContext reference. The
+/// toggles it backs (signups, etc.) are checked on rare paths —
+/// account creation hits this once per signup attempt, which is
+/// dwarfed by everything else the request does.
+/// </summary>
+public class ServerSettingsService(DorkNetDbContext db)
+{
+    private const int RowId = 1;
+
+    public async Task<ServerSettingsEntity> GetAsync()
+    {
+        var row = await db.ServerSettings.AsNoTracking()
+            .FirstOrDefaultAsync(s => s.Id == RowId);
+        return row ?? new ServerSettingsEntity { Id = RowId };
+    }
+
+    public async Task<bool> AreSignupsDisabledAsync()
+    {
+        var row = await db.ServerSettings.AsNoTracking()
+            .FirstOrDefaultAsync(s => s.Id == RowId);
+        return row?.SignupsDisabled ?? false;
+    }
+
+    public async Task<ServerSettingsEntity> SetSignupsDisabledAsync(bool disabled)
+    {
+        var existing = await db.ServerSettings.FirstOrDefaultAsync(s => s.Id == RowId);
+        if (existing is null)
+        {
+            existing = new ServerSettingsEntity
+            {
+                Id = RowId,
+                SignupsDisabled = disabled,
+                UpdatedAt = DateTime.UtcNow,
+            };
+            db.ServerSettings.Add(existing);
+        }
+        else
+        {
+            existing.SignupsDisabled = disabled;
+            existing.UpdatedAt = DateTime.UtcNow;
+        }
+        await db.SaveChangesAsync();
+        return existing;
+    }
+}