refactor(bootstrap): migrate default decks to seed file

Extracts /deck/info's default_deck_list into seeds/default-decks.json
via the new extract-default-decks.ps1 PowerShell script and imports
through DefaultDeckImporter. The importer carries the same orphan-
card-id warning the old GlobalsImporter path emitted; production cards
yield 0 orphans. WarnOrphans stays inside GlobalsImporter for now —
SpotCards/ReprintedCards/UnlimitedRestrictions/LoadingExclusionCards
still use it until Task 9.

Part of the bootstrap seed refactor (Task 6).

SVSim.UnitTests/Importers/DefaultDeckImporterTests.cs

@@ -0,0 +1,120 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Bootstrap.Importers;
+using SVSim.Database;
+using SVSim.Database.Models;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Importers;
+
+public class DefaultDeckImporterTests
+{
+    private static string SeedDir => Path.Combine(AppContext.BaseDirectory, "Data", "seeds");
+
+    [Test]
+    public async Task Imports_default_decks_from_seed_file()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new DefaultDeckImporter().ImportAsync(db, SeedDir);
+
+        var decks = await db.DefaultDecks.OrderBy(d => d.Id).ToListAsync();
+        Assert.That(decks.Count, Is.GreaterThan(0), "seed file must contain default decks");
+        Assert.That(decks.All(d => d.ClassId > 0), Is.True);
+        Assert.That(decks.All(d => !string.IsNullOrEmpty(d.DeckName)), Is.True);
+        // CardIdArray is a JSON array column; every row must serialize as such.
+        Assert.That(decks.All(d => d.CardIdArray.StartsWith("[")), 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 DefaultDeckImporter().ImportAsync(db, SeedDir);
+        int before = await db.DefaultDecks.CountAsync();
+        await new DefaultDeckImporter().ImportAsync(db, SeedDir);
+        int after = await db.DefaultDecks.CountAsync();
+
+        Assert.That(after, Is.EqualTo(before));
+    }
+
+    [Test]
+    public async Task Leaves_existing_rows_untouched_when_missing_from_seed()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        const int legacyId = 99999;
+        db.DefaultDecks.Add(new DefaultDeckEntry
+        {
+            Id = legacyId,
+            ClassId = 1,
+            SleeveId = 0,
+            LeaderSkinId = 0,
+            DeckName = "legacy",
+            CardIdArray = "[]",
+        });
+        await db.SaveChangesAsync();
+
+        await new DefaultDeckImporter().ImportAsync(db, SeedDir);
+
+        var legacy = await db.DefaultDecks.FindAsync(legacyId);
+        Assert.That(legacy, Is.Not.Null, "seed-missing row must be left intact");
+        Assert.That(legacy!.DeckName, Is.EqualTo("legacy"));
+    }
+
+    [Test]
+    public async Task Skips_rows_with_zero_id()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        string tmp = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}");
+        Directory.CreateDirectory(tmp);
+        try
+        {
+            File.WriteAllText(Path.Combine(tmp, "default-decks.json"),
+                "[{\"id\":0,\"class_id\":1,\"sleeve_id\":0,\"leader_skin_id\":0,\"deck_name\":\"junk\",\"card_id_array\":[1,2,3]}]");
+
+            await new DefaultDeckImporter().ImportAsync(db, tmp);
+
+            int count = await db.DefaultDecks.CountAsync();
+            Assert.That(count, Is.EqualTo(0), "rows with id=0 must not be inserted");
+        }
+        finally { Directory.Delete(tmp, true); }
+    }
+
+    [Test]
+    public async Task Warns_on_orphan_card_ids_but_does_not_fail()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        // The test factory's minimal seed contains only cards 10001001/10001002/10001003.
+        // Reference a card id well outside that set so the orphan-count branch fires.
+        string tmp = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}");
+        Directory.CreateDirectory(tmp);
+        try
+        {
+            File.WriteAllText(Path.Combine(tmp, "default-decks.json"),
+                "[{\"id\":1234,\"class_id\":1,\"sleeve_id\":0,\"leader_skin_id\":0,\"deck_name\":\"orphans\",\"card_id_array\":[999999999,888888888]}]");
+
+            Assert.DoesNotThrowAsync(async () =>
+                await new DefaultDeckImporter().ImportAsync(db, tmp),
+                "orphan card_ids must warn, never throw");
+
+            var row = await db.DefaultDecks.FindAsync(1234);
+            Assert.That(row, Is.Not.Null, "deck must be inserted even with orphan card refs");
+            Assert.That(row!.DeckName, Is.EqualTo("orphans"));
+        }
+        finally { Directory.Delete(tmp, true); }
+    }
+}