Add multi-country ITAD deals, configurable currency, and per-source filtering

- ITAD deals can now be fetched from multiple countries simultaneously via
  ITAD_COUNTRIES (e.g. US,CA,GB,DE). Deals are merged across regions and
  deduplicated by game+shop, with the first country taking priority.

- Prices from non-USD regions are normalised to USD using exchange rates
  so filtering (max price) works consistently across countries.

- ITAD results are now sorted by newest deals first (client-side by
  timestamp) instead of only by highest discount, reducing missed deals.

- Default fetch limit raised from 20 to 100 to capture more deals.

- Display currency is now configurable: DEFAULT_CURRENCY sets the primary
  currency shown first, EXTRA_CURRENCIES sets additional ones. All
  Frankfurter-supported currencies are available with proper symbols.

- Filtering is now per-source with dedicated env vars:
  CHEAPSHARK_MIN_DISCOUNT, CHEAPSHARK_MIN_RATING, CHEAPSHARK_MAX_PRICE,
  ITAD_MIN_DISCOUNT, ITAD_MAX_PRICE, ITAD_DEALS_LIMIT. Shared fallbacks
  (MIN_DISCOUNT_PERCENT, MAX_PRICE) are still supported. Legacy
  MAX_PRICE_USD and MIN_DEAL_RATING continue to work as fallbacks.

https://claude.ai/code/session_01EfPjktyrF24DBNHWsY1KBP

gaming_deals_bot/config.py

@@ -20,10 +20,47 @@ class Config:
             s.strip().lower() for s in raw_sources.split(",") if s.strip()
         ]
 
-        # Deal filtering
-        self.min_deal_rating = float(os.environ.get("MIN_DEAL_RATING", "8.0"))
-        self.min_discount_percent = int(os.environ.get("MIN_DISCOUNT_PERCENT", "50"))
-        self.max_price_usd = float(os.environ.get("MAX_PRICE_USD", "20"))
+        # ITAD countries: comma-separated ISO 3166-1 alpha-2 country codes
+        # Deals are fetched for each country and merged (first country has priority
+        # when the same game appears in multiple regions).
+        raw_countries = os.environ.get("ITAD_COUNTRIES", "US")
+        self.itad_countries: list[str] = [
+            c.strip().upper() for c in raw_countries.split(",") if c.strip()
+        ]
+
+        # Currency display
+        self.default_currency = os.environ.get("DEFAULT_CURRENCY", "USD").upper()
+        raw_extra = os.environ.get("EXTRA_CURRENCIES", "CAD,EUR,GBP")
+        self.extra_currencies: list[str] = [
+            c.strip().upper() for c in raw_extra.split(",") if c.strip()
+        ]
+
+        # Shared filter fallbacks (support legacy env vars)
+        _max_price = os.environ.get(
+            "MAX_PRICE", os.environ.get("MAX_PRICE_USD", "20")
+        )
+        _min_discount = os.environ.get("MIN_DISCOUNT_PERCENT", "50")
+        _min_rating = os.environ.get("MIN_DEAL_RATING", "8.0")
+
+        # CheapShark-specific filtering (falls back to shared values)
+        self.cheapshark_min_discount = int(
+            os.environ.get("CHEAPSHARK_MIN_DISCOUNT", _min_discount)
+        )
+        self.cheapshark_min_rating = float(
+            os.environ.get("CHEAPSHARK_MIN_RATING", _min_rating)
+        )
+        self.cheapshark_max_price = float(
+            os.environ.get("CHEAPSHARK_MAX_PRICE", _max_price)
+        )
+
+        # ITAD-specific filtering (falls back to shared values)
+        self.itad_min_discount = int(
+            os.environ.get("ITAD_MIN_DISCOUNT", _min_discount)
+        )
+        self.itad_max_price = float(
+            os.environ.get("ITAD_MAX_PRICE", _max_price)
+        )
+        self.itad_deals_limit = int(os.environ.get("ITAD_DEALS_LIMIT", "100"))
 
         # Intro message on startup
         self.send_intro_message = os.environ.get(