feat(packs): PackDrawTableImporter with fixture tests

Idempotent upsert keyed on pack_id; slot rates and card weights are
wiped per pack and reinserted. String slot/tier in the seed translate
to enum at import time.

Tests:
- Imports_config_slot_rates_and_card_weights
- Is_idempotent_on_rerun

Fixtures live under SVSim.Bootstrap/Data/test-fixtures/seeds/ and overlay
the production seeds via the existing csproj rule (test-fixture file
beats production file at same Link path).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.UnitTests/Importers/PackDrawTableImporterTests.cs

@@ -0,0 +1,48 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Bootstrap.Importers;
+using SVSim.Database;
+using SVSim.Database.Enums;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Importers;
+
+public class PackDrawTableImporterTests
+{
+    private static string SeedDir => Path.Combine(AppContext.BaseDirectory, "Data", "seeds");
+
+    [Test]
+    public async Task Imports_config_slot_rates_and_card_weights()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new PackDrawTableImporter().ImportAsync(db, SeedDir);
+
+        Assert.That(await db.PackDrawConfigs.CountAsync(), Is.EqualTo(2));
+        Assert.That(await db.PackDrawSlotRates.CountAsync(), Is.EqualTo(8));
+        Assert.That(await db.PackDrawCardWeights.CountAsync(), Is.EqualTo(5));
+
+        var bonus = await db.PackDrawCardWeights
+            .Where(w => w.PackId == 98001 && w.Slot == DrawSlot.Bonus)
+            .ToListAsync();
+        Assert.That(bonus.Count, Is.EqualTo(2));
+        Assert.That(bonus.All(w => w.RatePct == null && w.IsLeader && w.Tier == DrawTier.Special), Is.True);
+    }
+
+    [Test]
+    public async Task Is_idempotent_on_rerun()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new PackDrawTableImporter().ImportAsync(db, SeedDir);
+        int before = await db.PackDrawCardWeights.CountAsync();
+        await new PackDrawTableImporter().ImportAsync(db, SeedDir);
+        int after = await db.PackDrawCardWeights.CountAsync();
+
+        Assert.That(after, Is.EqualTo(before));
+    }
+}