feat(config): add Freeplay config section (default off)

Adds FreeplayConfig [ConfigSection("Freeplay")] with Enabled=false,
CurrencyAmount=99999, CardCopies=3, and ShippedDefaults(). Covered by
FreeplayConfigTests verifying the tier-chain resolves shipped defaults.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.Database/Models/Config/FreeplayConfig.cs

@@ -0,0 +1,17 @@
+namespace SVSim.Database.Models.Config;
+
+/// <summary>
+/// Global "freeplay" toggle. When <see cref="Enabled"/>, every viewer is treated (in logic,
+/// never in the DB) as owning all cards (<see cref="CardCopies"/> each), all cosmetics, and
+/// <see cref="CurrencyAmount"/> of Crystal/Rupee/Red-Ether. See
+/// docs/superpowers/specs/2026-05-29-freeplay-mode-design.md.
+/// </summary>
+[ConfigSection("Freeplay")]
+public class FreeplayConfig
+{
+    public bool Enabled { get; set; } = false;
+    public ulong CurrencyAmount { get; set; } = 99999;
+    public int CardCopies { get; set; } = 3;
+
+    public static FreeplayConfig ShippedDefaults() => new();
+}

SVSim.UnitTests/Services/FreeplayConfigTests.cs

@@ -0,0 +1,26 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Database;
+using SVSim.Database.Models.Config;
+using SVSim.EmulatedEntrypoint.Services;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Services;
+
+public class FreeplayConfigTests
+{
+    [Test]
+    public void Freeplay_defaults_to_disabled_with_canonical_amounts()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        var svc = new GameConfigService(db, new ConfigurationBuilder().Build());
+
+        var cfg = svc.Get<FreeplayConfig>();
+
+        Assert.That(cfg.Enabled, Is.False, "freeplay must be off unless explicitly enabled");
+        Assert.That(cfg.CurrencyAmount, Is.EqualTo(99999UL));
+        Assert.That(cfg.CardCopies, Is.EqualTo(3));
+    }
+}