feat(matching): IBotRoster + hardcoded BotRoster fixture (8 bots, one per class)

AIBotProfile carries the cosmetic metadata the AI rank-battle start
endpoint composes into oppo_info. BotRoster.Pick is deterministic per
MatchContext so mid-flight retries get the same opponent. ai_id values
4001..4008 are placeholders per the existing ai-start.md TODO — we have
no live capture of the prod catalog.

Future improvement: migrate Roster to a bot-roster.json seed under
SVSim.Bootstrap/Data/seeds/ for editability without rebuilds.

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

SVSim.UnitTests/Matching/BotRosterTests.cs

@@ -0,0 +1,48 @@
+using NUnit.Framework;
+using SVSim.BattleNode.Bridge;
+using SVSim.EmulatedEntrypoint.Matching;
+
+namespace SVSim.UnitTests.Matching;
+
+[TestFixture]
+public class BotRosterTests
+{
+    private static MatchContext Ctx(string userName, string classId) => new(
+        SelfDeckCardIds: Array.Empty<long>(),
+        ClassId: classId, CharaId: classId, CardMasterName: "card_master_node_10015",
+        CountryCode: "JP", UserName: userName, SleeveId: "0",
+        EmblemId: "0", DegreeId: "0", FieldId: 0, IsOfficial: 0, BattleType: 11);
+
+    [Test]
+    public void Pick_returns_a_bot_with_valid_ai_id()
+    {
+        var roster = new BotRoster();
+        var bot = roster.Pick(Ctx("PlayerA", "1"));
+
+        Assert.That(bot.AiId, Is.InRange(4001, 4008));
+    }
+
+    [Test]
+    public void Pick_returns_bot_with_class_metadata_set()
+    {
+        var roster = new BotRoster();
+        var bot = roster.Pick(Ctx("PlayerA", "1"));
+
+        Assert.That(bot.ClassId, Is.InRange(1, 8));
+        Assert.That(bot.CharaId, Is.InRange(1, 8));
+        Assert.That(bot.UserName, Is.Not.Null.And.Not.Empty);
+        Assert.That(bot.CountryCode, Is.EqualTo("NONE"));
+    }
+
+    [Test]
+    public void Pick_is_deterministic_per_match_context()
+    {
+        var roster = new BotRoster();
+        var ctx = Ctx("PlayerA", "3");
+
+        var a = roster.Pick(ctx);
+        var b = roster.Pick(ctx);
+
+        Assert.That(a, Is.EqualTo(b), "Same ctx → same bot, so mid-flight retries get the same opponent.");
+    }
+}