Fix account_risk_state missing on PostgreSQL: probe table before cache skip.

Co-authored-by: Cursor <cursoragent@cursor.com>

db_conn.py

@@ -120,6 +120,14 @@ def is_schema_migration_error(exc: BaseException) -> bool:
     return False
 
 
+def is_missing_relation_error(exc: BaseException) -> bool:
+    """表/视图不存在。"""
+    if is_schema_migration_error(exc):
+        msg = str(exc).lower()
+        return any(x in msg for x in ("no such table", "does not exist", "undefined table"))
+    return False
+
+
 def rollback_if_postgres(conn: "DbConnection") -> None:
     if is_postgres():
         try: