Use CheapShark's native 0-10 scale for MIN_DEAL_RATING

The previous 0-100 scale with a * 10 conversion was confusing —
CheapShark returns deal ratings as floats (e.g. 9.8, 7.5) so the
config should match. Default is now 8.0 instead of 80.

https://claude.ai/code/session_01LPpSZFfyh6vdV5HGFWjoQX

gaming_deals_bot/cheapshark.py

@@ -75,7 +75,7 @@ async def fetch_deals(
 
         if savings < min_discount:
             continue
-        if rating * 10 < min_rating:  # dealRating is 0-10, config is 0-100
+        if rating < min_rating:
             continue
 
         steam_app_id = d.get("steamAppID") or None