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/bot.py

@@ -7,6 +7,7 @@ import httpx
 
 from .cheapshark import CheapSharkDeal, fetch_deals
 from .config import Config
+from .currency import refresh_rates
 from .database import Database
 from .epic import EpicFreeGame, fetch_free_games
 from .formatter import format_deal, format_epic_free, format_epic_upcoming
@@ -30,9 +31,12 @@ class DealsBot:
         self._first_run_done = False
 
     async def start(self):
-        """Initialize database and run first-run population."""
+        """Initialize database, fetch exchange rates, and run first-run population."""
         await self.db.connect()
 
+        # Pre-fetch exchange rates so the first deal post has conversions
+        await refresh_rates(self._http)
+
         first_run = await self.db.get_config("first_run_done")
         if first_run != "true":
             logger.info("First run detected — populating database without posting")