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/Controllers/API/Activities/ActivitiesController.cs

@@ -0,0 +1,16 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace DorkNet.Server.Controllers.API.Activities;
+
+/// <summary>
+/// api.{rec.net,localhost}/api/activities/* — per-activity content
+/// (charades words, party-game prompts, etc.). The 2020 watch
+/// fetches these as a static list at room-join time; we ship an
+/// empty list so the activity's bundled defaults kick in.
+/// </summary>
+[ApiController]
+public class ActivitiesController : ControllerBase
+{
+    [HttpGet("api/activities/charades/v1/words")]
+    public IActionResult CharadesWords() => Ok(Array.Empty<object>());
+}