fix: security, data-integrity, and doc-drift findings from repo audit

Consolidates duplicate KIS API client implementations (governance tests
were exercising an unused class instead of the one actually running in
production), closes a SQL injection path in the DB admin page, fixes a
migration that used MySQL-only syntax and had never actually applied
(confirmed against production), resyncs docs/db/quantengine.dbml with
all migrations, and removes a duplicate OMS·WMS·ERP frontend tree in
favor of src/frontend/. Also corrects several unverifiable/inflated
claims in the OMS planning docs and realigns CI/CD and architecture
documentation with what's actually in the repo.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -28,6 +28,12 @@ src/dotnet/QuantEngine.Web/wwwroot/_framework/
 # 런타임 감사 로그 (append-only, 매 DAG 실행마다 증가)
 runtime/lineage_events.jsonl
 
+# .NET 런타임 로그 (Serilog 등, 실행마다 재생성)
+**/logs/*.log
+
+# Playwright 테스트 산출물 (스크린샷/트레이스, 실행마다 재생성)
+test-results/
+
 # OS / 에디터
 ...
 .DS_Store