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

backend/apps/news_service.py

@@ -28,11 +28,11 @@ def create_app() -> FastAPI:
     add_cors_middleware(app)
 
     @app.get("/health")
-    async def health_check() -> dict[str, str]:
+    def health_check() -> dict[str, str]:
         return {"status": "healthy", "service": "news-service"}
 
     @app.get("/api/enriched-news")
-    async def api_get_enriched_news(
+    def api_get_enriched_news(
         ticker: str = Query(..., min_length=1),
         start_date: str | None = Query(None),
         end_date: str | None = Query(None),
@@ -49,7 +49,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/news-for-date")
-    async def api_get_news_for_date(
+    def api_get_news_for_date(
         ticker: str = Query(..., min_length=1),
         date: str = Query(...),
         limit: int = Query(20, ge=1, le=100),
@@ -64,7 +64,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/news-timeline")
-    async def api_get_news_timeline(
+    def api_get_news_timeline(
         ticker: str = Query(..., min_length=1),
         start_date: str = Query(...),
         end_date: str = Query(...),
@@ -79,7 +79,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/categories")
-    async def api_get_categories(
+    def api_get_categories(
         ticker: str = Query(..., min_length=1),
         start_date: str | None = Query(None),
         end_date: str | None = Query(None),
@@ -96,7 +96,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/similar-days")
-    async def api_get_similar_days(
+    def api_get_similar_days(
         ticker: str = Query(..., min_length=1),
         date: str = Query(...),
         n_similar: int = Query(5, ge=1, le=20),
@@ -111,7 +111,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/stories/{ticker}")
-    async def api_get_story(
+    def api_get_story(
         ticker: str,
         as_of_date: str = Query(...),
         store: MarketStore = Depends(get_market_store),
@@ -124,7 +124,7 @@ def create_app() -> FastAPI:
         )
 
     @app.get("/api/range-explain")
-    async def api_get_range_explain(
+    def api_get_range_explain(
         ticker: str = Query(..., min_length=1),
         start_date: str = Query(...),
         end_date: str = Query(...),