Add multi-currency pricing (USD, CAD, EUR, GBP) for deal posts

Fetches live exchange rates from the Frankfurter API (ECB data, free,
no API key) and displays converted prices alongside USD in every deal
message. Rates are cached in memory and auto-refreshed hourly.

https://claude.ai/code/session_01LPpSZFfyh6vdV5HGFWjoQX

gaming_deals_bot/formatter.py

@@ -8,6 +8,7 @@ from datetime import datetime, timezone
 import markdown
 
 from .cheapshark import CheapSharkDeal
+from .currency import format_price
 from .epic import EpicFreeGame
 
 _md = markdown.Markdown()
@@ -25,9 +26,16 @@ def format_deal(deal: CheapSharkDeal, is_historical_low: bool = False) -> tuple[
     Returns (body, formatted_body).
     """
     discount = int(deal.savings)
+    sale_price = float(deal.sale_price)
+    normal_price = float(deal.normal_price)
+
+    sale_multi = format_price(sale_price)
+    normal_display = format_price(normal_price)
+
     lines = [
         f"**🎮 [DEAL] {deal.title}**",
-        f"> {discount}% off — **${deal.sale_price}** on {deal.store_name} ~~${deal.normal_price}~~",
+        f"> {discount}% off on {deal.store_name} ~~{normal_display}~~",
+        f"> 💰 **{sale_multi}**",
     ]
 
     if is_historical_low:
@@ -41,7 +49,8 @@ def format_deal(deal: CheapSharkDeal, is_historical_low: bool = False) -> tuple[
     # Plain text fallback — strip markdown syntax
     plain_lines = [
         f"🎮 [DEAL] {deal.title}",
-        f"  {discount}% off — ${deal.sale_price} on {deal.store_name} (was ${deal.normal_price})",
+        f"  {discount}% off on {deal.store_name} (was {normal_display})",
+        f"  💰 {sale_multi}",
     ]
     if is_historical_low:
         plain_lines.append("  🏆 All-time low!")