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.EmulatedEntrypoint/Matching/IBotRoster.cs

@@ -0,0 +1,21 @@
+using SVSim.BattleNode.Bridge;
+
+namespace SVSim.EmulatedEntrypoint.Matching;
+
+/// <summary>
+/// Picks a bot opponent for an incoming AI rank battle. Used by
+/// <c>RankBattleController.AiStart</c> to compose <c>oppo_info</c>.
+/// </summary>
+/// <remarks>
+/// Phase 3 ships a hardcoded fixture; future improvement is to migrate the roster
+/// to <c>SVSim.Bootstrap/Data/seeds/bot-roster.json</c> for editability without
+/// rebuilds. See spec § Future improvements.
+/// </remarks>
+public interface IBotRoster
+{
+    /// <summary>
+    /// Returns a bot profile for the calling viewer. Deterministic per
+    /// <see cref="MatchContext"/> — the same context value returns the same bot.
+    /// </summary>
+    AIBotProfile Pick(MatchContext selfCtx);
+}