added bounded close session for curl_cffi/past_prices to pricing model

src/monitor_utils/models.py

@@ -54,12 +54,14 @@ class PricingInfo:
         current_price: Current listed price.
         price_before_drop: Stored price prior to the last detected drop.
         edu_price: Education-store price when offered.
+        past_prices: Prior price history as price/date entries, oldest first.
     """
 
     original_price: float
     current_price: float
     price_before_drop: float | None = None
     edu_price: float | None = None
+    past_prices: list[dict] | None = None
 
 
 @dataclass