feat(bootstrap): ArenaTwoPickRewardImporter + tests

Idempotent upsert importer for arena-two-pick-rewards.json; 2 NUnit tests
(16-row load + idempotency). Wired into Program.cs globals pipeline after
ArenaSeasonImporter.

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

SVSim.Bootstrap/Importers/ArenaTwoPickRewardImporter.cs

@@ -0,0 +1,51 @@
+using Microsoft.EntityFrameworkCore;
+using SVSim.Bootstrap.Models.Seed;
+using SVSim.Database;
+using SVSim.Database.Models;
+
+namespace SVSim.Bootstrap.Importers;
+
+/// <summary>
+/// Idempotent upsert of <see cref="ArenaTwoPickReward"/> rows from
+/// <c>arena-two-pick-rewards.json</c>. Key = (WinCount, RewardType, RewardId).
+/// </summary>
+public class ArenaTwoPickRewardImporter
+{
+    public async Task<int> ImportAsync(SVSimDbContext context, string seedDir)
+    {
+        var path = Path.Combine(seedDir, "arena-two-pick-rewards.json");
+        if (!File.Exists(path))
+        {
+            Console.WriteLine($"[ArenaTwoPickRewardImporter] missing {path}; skipping.");
+            return 0;
+        }
+
+        var seeds = SeedLoader.LoadList<ArenaTwoPickRewardSeed>(path);
+        var existing = await context.ArenaTwoPickRewards
+            .ToDictionaryAsync(r => (r.WinCount, r.RewardType, r.RewardId));
+
+        int upserted = 0;
+        foreach (var s in seeds)
+        {
+            if (existing.TryGetValue((s.WinCount, s.RewardType, s.RewardId), out var row))
+            {
+                row.RewardNum = s.RewardNum;
+            }
+            else
+            {
+                context.ArenaTwoPickRewards.Add(new ArenaTwoPickReward
+                {
+                    WinCount  = s.WinCount,
+                    RewardType = s.RewardType,
+                    RewardId  = s.RewardId,
+                    RewardNum = s.RewardNum,
+                });
+            }
+            upserted++;
+        }
+
+        await context.SaveChangesAsync();
+        Console.WriteLine($"[ArenaTwoPickRewardImporter] upserted={upserted}");
+        return upserted;
+    }
+}

SVSim.Bootstrap/Program.cs

@@ -84,6 +84,7 @@ public static class Program
             await new MyRotationImporter().ImportAsync(context, opts.SeedDir);
             await new AvatarAbilityImporter().ImportAsync(context, opts.SeedDir);
             await new ArenaSeasonImporter().ImportAsync(context, opts.SeedDir);
+            await new ArenaTwoPickRewardImporter().ImportAsync(context, opts.SeedDir);
             await new BattlePassImporter().ImportAsync(context, opts.SeedDir);
             await new BattlePassSeasonImporter().ImportAsync(context, opts.SeedDir);
             await new BattlePassRewardImporter().ImportAsync(context, opts.SeedDir);

SVSim.UnitTests/Importers/ArenaTwoPickRewardImporterTests.cs

@@ -0,0 +1,62 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Bootstrap.Importers;
+using SVSim.Database;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Importers;
+
+public class ArenaTwoPickRewardImporterTests
+{
+    private static async Task<SVSimDbContext> CreateContextAsync()
+    {
+        var factory = new SVSimTestFactory();
+        var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+        await db.Database.EnsureCreatedAsync();
+        return db;
+    }
+
+    [Test]
+    public async Task Import_loads_all_16_rows_from_seed_file()
+    {
+        await using var db = await CreateContextAsync();
+        var importer = new ArenaTwoPickRewardImporter();
+
+        await importer.ImportAsync(db, FindSeedDir());
+
+        var rows = await db.ArenaTwoPickRewards.OrderBy(r => r.WinCount).ThenBy(r => r.RewardType).ToListAsync();
+        Assert.That(rows.Count, Is.EqualTo(16));
+        Assert.That(rows.Max(r => r.WinCount), Is.EqualTo(7));
+
+        var w0 = rows.Where(r => r.WinCount == 0).ToList();
+        Assert.That(w0.Count, Is.EqualTo(2));
+        Assert.That(w0.Single(r => r.RewardType == 4).RewardNum, Is.EqualTo(1));
+        Assert.That(w0.Single(r => r.RewardType == 9).RewardNum, Is.EqualTo(100));
+
+        var w7 = rows.Where(r => r.WinCount == 7).ToList();
+        Assert.That(w7.Single(r => r.RewardType == 4).RewardNum, Is.EqualTo(2));
+        Assert.That(w7.Single(r => r.RewardType == 9).RewardNum, Is.EqualTo(1500));
+    }
+
+    [Test]
+    public async Task Import_is_idempotent_on_re_run()
+    {
+        await using var db = await CreateContextAsync();
+        var importer = new ArenaTwoPickRewardImporter();
+
+        await importer.ImportAsync(db, FindSeedDir());
+        await importer.ImportAsync(db, FindSeedDir());
+
+        var count = await db.ArenaTwoPickRewards.CountAsync();
+        Assert.That(count, Is.EqualTo(16), "second import should upsert, not duplicate");
+    }
+
+    private static string FindSeedDir()
+    {
+        var dir = Path.Combine(AppContext.BaseDirectory, "Data", "seeds");
+        if (!Directory.Exists(dir))
+            throw new DirectoryNotFoundException($"seeds dir not found at {dir} — verify csproj copy");
+        return dir;
+    }
+}