feat(matching): move BotRoster from hardcoded fixture to DB-backed seed

Phase 3 shipped the AI rank battle bot pool as a hardcoded 8-entry list
inlined in SVSim.EmulatedEntrypoint/Matching/BotRoster.cs — editing meant
recompiling. Per PLAN.md 2026-06-02 item (d), move it to a Bootstrap
importer so the roster lives in seeds/bot-roster.json and the DB.

Shape mirrors PracticeOpponent end-to-end:
- BotRosterEntry (SVSim.Database/Models) — PK = AiId via the Id passthrough
  pattern. DbSet<BotRosterEntry> BotRoster on SVSimDbContext.
- AddBotRoster migration (DDL only, per migrations-are-DDL-only rule).
- seeds/bot-roster.json — 8 rows preserving the current prod-verified
  cosmetic ids (sleeve 704141010 / emblem 400001100 / degree 120027 /
  field 5) and series-1 ai_ids from rm_ai_setting.csv (1111..1181).
- BotRosterSeed POCO + BotRosterImporter (idempotent upsert keyed by AiId,
  leaves seed-missing rows intact). Wired into SVSim.Bootstrap/Program.cs
  next to PracticeOpponentImporter.
- IGlobalsRepository.GetBotRoster() + impl.

IBotRoster.Pick → PickAsync because BotRoster now depends on the transient
IGlobalsRepository. RankBattleController awaits the new signature. The
deterministic hash-on-ctx invariant (same ctx → same bot, so /ai_<fmt>/start
retries pick the same opponent) is preserved.

DI: AddSingleton<IBotRoster> → AddTransient (matches IGlobalsRepository's
lifetime). Test fixture's SeedGlobalsAsync also runs the importer so
RankBattleControllerTests + the rewritten BotRosterTests both see seeded
rows.

Tests: 931 → 936 passing. Existing 3 BotRosterTests reshaped for the DB
backing + 1 new "throws on empty roster" guard; 4 new
BotRosterImporterTests mirror PracticeOpponentImporterTests
(round-trip / idempotent / seed-missing-row-intact / ai_id=0 skip).

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

SVSim.EmulatedEntrypoint/Program.cs

@@ -138,8 +138,9 @@ public class Program
             new ModePolicy("unlimited_rank_battle", PolicyKind.PvpFirstThenAiFallback),
         }));
         builder.Services.AddSingleton<IMatchingPairUpService, InProcessPairUp>();
-        // Phase 3: bot fixture used by RankBattleController.AiStart to compose oppo_info.
-        builder.Services.AddSingleton<IBotRoster, BotRoster>();
+        // Phase 3: bot roster used by RankBattleController.AiStart to compose oppo_info.
+        // Transient because BotRoster depends on the transient IGlobalsRepository.
+        builder.Services.AddTransient<IBotRoster, BotRoster>();
 
         builder.Services.AddTransient<ShadowverseTranslationMiddleware>();
         builder.Services.AddTransient<SessionidMappingMiddleware>();