perf: optimize system concurrency, I/O stability and fix WebSocket disconnects

backend/apps/trading_service.py

@@ -29,12 +29,12 @@ def create_app() -> FastAPI:
     add_cors_middleware(app)
 
     @app.get("/health")
-    async def health_check() -> dict[str, str]:
+    def health_check() -> dict[str, str]:
         """Health check endpoint."""
         return {"status": "healthy", "service": "trading-service"}
 
     @app.get("/api/prices", response_model=PriceResponse)
-    async def api_get_prices(
+    def api_get_prices(
         ticker: str = Query(..., min_length=1),
         start_date: str = Query(...),
         end_date: str = Query(...),
@@ -47,7 +47,7 @@ def create_app() -> FastAPI:
         return PriceResponse(ticker=payload["ticker"], prices=payload["prices"])
 
     @app.get("/api/financials", response_model=FinancialMetricsResponse)
-    async def api_get_financials(
+    def api_get_financials(
         ticker: str = Query(..., min_length=1),
         end_date: str = Query(...),
         period: str = Query("ttm"),
@@ -62,7 +62,7 @@ def create_app() -> FastAPI:
         return FinancialMetricsResponse(financial_metrics=payload["financial_metrics"])
 
     @app.get("/api/news", response_model=CompanyNewsResponse)
-    async def api_get_news(
+    def api_get_news(
         ticker: str = Query(..., min_length=1),
         end_date: str = Query(...),
         start_date: str | None = Query(None),
@@ -77,7 +77,7 @@ def create_app() -> FastAPI:
         return CompanyNewsResponse(news=payload["news"])
 
     @app.get("/api/insider-trades", response_model=InsiderTradeResponse)
-    async def api_get_insider_trades(
+    def api_get_insider_trades(
         ticker: str = Query(..., min_length=1),
         end_date: str = Query(...),
         start_date: str | None = Query(None),
@@ -92,12 +92,12 @@ def create_app() -> FastAPI:
         return InsiderTradeResponse(insider_trades=payload["insider_trades"])
 
     @app.get("/api/market/status")
-    async def api_get_market_status() -> dict[str, Any]:
+    def api_get_market_status() -> dict[str, Any]:
         """Return current market status using the existing market service logic."""
         return trading_domain.get_market_status_payload()
 
     @app.get("/api/market-cap")
-    async def api_get_market_cap(
+    def api_get_market_cap(
         ticker: str = Query(..., min_length=1),
         end_date: str = Query(...),
     ) -> dict[str, Any]:
@@ -108,7 +108,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/line-items", response_model=LineItemResponse)
-    async def api_get_line_items(
+    def api_get_line_items(
         ticker: str = Query(..., min_length=1),
         line_items: list[str] = Query(...),
         end_date: str = Query(...),