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/Auth/AdminOnlyAttribute.cs

@@ -0,0 +1,49 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.EntityFrameworkCore;
+using DorkNet.Server.Data;
+
+namespace DorkNet.Server.Auth;
+
+/// <summary>
+/// Action / controller filter that 403s any request whose
+/// JWT-resolved player doesn't have <c>IsAdmin == true</c>. Does not
+/// itself authenticate — pair it with <c>[Authorize]</c> to ensure a
+/// valid bearer is present before this runs.
+///
+/// Usage:
+/// <code>
+/// [Authorize]
+/// [AdminOnly]
+/// [Route("api/admin/v1")]
+/// public class AdminController { ... }
+/// </code>
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false)]
+public class AdminOnlyAttribute : Attribute, IAsyncAuthorizationFilter
+{
+    public async Task OnAuthorizationAsync(AuthorizationFilterContext context)
+    {
+        // AuthorizationFilterContext.HttpContext is always populated and
+        // exposes the same ClaimsPrincipal a controller would see, so
+        // there's no reason to round-trip through IHttpContextAccessor
+        // (which isn't even registered in this app's DI container — the
+        // earlier lookup crashed every admin request with
+        // "No service for type IHttpContextAccessor has been registered").
+        if (ControllerBaseExtensions.CurrentPlayerId(context.HttpContext.User) is not long id)
+        {
+            // No JWT → defer to [Authorize]'s 401.
+            context.Result = new UnauthorizedResult();
+            return;
+        }
+
+        var db = context.HttpContext.RequestServices
+            .GetRequiredService<DorkNetDbContext>();
+        var isAdmin = await db.Players
+            .Where(p => p.Id == id)
+            .Select(p => p.IsAdmin)
+            .FirstOrDefaultAsync();
+        if (!isAdmin)
+            context.Result = new ForbidResult();
+    }
+}