fix: 대시보드 mode 배지 os.getenv 대신 settings.MODE 사용 (#237)

os.getenv("MODE")는 .env 파일을 읽지 못해 항상 paper를 반환함.
create_dashboard_app에 mode 파라미터 추가 후 main.py에서
settings.MODE를 직접 전달하도록 수정.

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

src/dashboard/app.py

@@ -13,10 +13,11 @@ from fastapi import FastAPI, HTTPException, Query
 from fastapi.responses import FileResponse
 
 
-def create_dashboard_app(db_path: str) -> FastAPI:
+def create_dashboard_app(db_path: str, mode: str = "paper") -> FastAPI:
     """Create dashboard FastAPI app bound to a SQLite database path."""
     app = FastAPI(title="The Ouroboros Dashboard", version="1.0.0")
     app.state.db_path = db_path
+    app.state.mode = mode
 
     @app.get("/")
     def index() -> FileResponse:
@@ -111,7 +112,7 @@ def create_dashboard_app(db_path: str) -> FastAPI:
 
             return {
                 "date": today,
-                "mode": os.getenv("MODE", "paper"),
+                "mode": mode,
                 "markets": market_status,
                 "totals": {
                     "trade_count": total_trades,