fix(zopk): Thread-safe DB session and connection pool for gthread workers

Create separate SessionLocal() in run_search() thread instead of sharing
main thread's session (SQLAlchemy sessions are not thread-safe). Increase
connection pool_size to 10 with pool_pre_ping for gthread worker support.

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

blueprints/admin/routes_zopk_news.py

@@ -618,14 +618,16 @@ def api_zopk_search_news_stream():
                 progress_queue.put((phase, message, current, total))
 
             def run_search():
+                search_db = SessionLocal()
                 try:
-                    service = ZOPKNewsService(db)
+                    service = ZOPKNewsService(search_db)
                     result_holder[0] = service.search_all_sources(
                         query, user_id=user_id, progress_callback=on_progress
                     )
                 except Exception as e:
                     error_holder[0] = e
                 finally:
+                    search_db.close()
                     progress_queue.put(None)  # sentinel
 
             thread = threading.Thread(target=run_search, daemon=True)

database.py

@@ -253,7 +253,7 @@ JSONB = JSONBType
 
 
 # Create engine
-engine = create_engine(DATABASE_URL, echo=False)
+engine = create_engine(DATABASE_URL, echo=False, pool_size=10, pool_pre_ping=True)
 SessionLocal = sessionmaker(bind=engine)
 Base = declarative_base()