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/CurrencyBalanceEntity.cs

@@ -0,0 +1,19 @@
+namespace DorkNet.Server.Data.Entities;
+
+/// <summary>
+/// Per-player wallet for a single currency. The 2020 client knows
+/// about a small set of <c>CurrencyType</c>s (1=Coins, 2=Tokens, …);
+/// each gets its own row keyed by (PlayerId, CurrencyType).
+///
+/// Updates go through <see cref="DorkNet.Server.Services.LevelService"/>
+/// or admin grants; reads back through the
+/// <c>storefronts/v4/balance/{currencyType}</c> endpoint.
+/// </summary>
+public class CurrencyBalanceEntity
+{
+    public long Id { get; set; }
+    public long PlayerId { get; set; }
+    public int CurrencyType { get; set; }
+    public long Balance { get; set; }
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}