fix(positions): sync latest scraper fixes from main repository

schwab_scraper/cli.py

@@ -134,7 +134,8 @@ async def async_main():
         return
 
     if args.positions is not None:
-        account_arg = args.positions or None
+        # If --positions has a value, use it. Otherwise, fall back to --account.
+        account_arg = args.positions if args.positions != "" else args.account
         envelope = await unified_api.get_positions(
             account=account_arg,
             include_non_equity=args.include_non_equity,