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/Data/Entities/CommunityBoardEntity.cs

@@ -0,0 +1,28 @@
+namespace DorkNet.Server.Data.Entities;
+
+/// <summary>
+/// Single-row table holding the dorm community board state. Replaces
+/// <c>data/community_board.json</c> on disk + in-memory cache so admin
+/// edits propagate across replicas without a file-watcher invalidation
+/// dance.
+///
+/// Only one row exists, with <see cref="Id"/> = 1. Reading is a single
+/// SELECT (cheap; the board is one document, not paginated). Writing
+/// is a single UPDATE — no synchronization needed because there's only
+/// ever one row to contend on, and admin edits are rare.
+/// </summary>
+public class CommunityBoardEntity
+{
+    /// <summary>Always 1. We model it as an int PK rather than a
+    /// composite or singleton-table pattern because EF Core needs a key
+    /// to track changes; pinning to id=1 keeps the upsert pattern
+    /// simple.</summary>
+    public int Id { get; set; } = 1;
+
+    /// <summary>JSON-serialised <c>CommunityBoardState</c>. Stored as
+    /// text rather than jsonb because we never query inside it — it's
+    /// loaded as a single blob and round-tripped to the client.</summary>
+    public string Json { get; set; } = "{}";
+
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}