Add gaming deals Matrix bot

Implements a Matrix bot that posts PC gaming deals and free game alerts:
- CheapShark API integration (Steam, GOG, Humble, GMG) polled every 2 hours
- Epic Games Store free games detection polled daily
- IsThereAnyDeal historical low price flagging (optional)
- SQLite deduplication with 30-day pruning
- First-run population (records existing deals without posting)
- Matrix-flavored HTML + plain text fallback messages
- Dockerfile for containerized deployment

https://claude.ai/code/session_01LPpSZFfyh6vdV5HGFWjoQX

gaming_deals_bot/config.py

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+import os
+
+
+class Config:
+    """Bot configuration loaded from environment variables."""
+
+    def __init__(self):
+        # Matrix settings
+        self.matrix_homeserver_url = self._require("MATRIX_HOMESERVER_URL")
+        self.matrix_bot_user_id = self._require("MATRIX_BOT_USER_ID")
+        self.matrix_bot_access_token = self._require("MATRIX_BOT_ACCESS_TOKEN")
+        self.matrix_deals_room_id = self._require("MATRIX_DEALS_ROOM_ID")
+
+        # ITAD API key (optional — historical low checks disabled without it)
+        self.itad_api_key = os.environ.get("ITAD_API_KEY", "")
+
+        # Deal filtering
+        self.min_deal_rating = int(os.environ.get("MIN_DEAL_RATING", "80"))
+        self.min_discount_percent = int(os.environ.get("MIN_DISCOUNT_PERCENT", "50"))
+        self.max_price_usd = float(os.environ.get("MAX_PRICE_USD", "20"))
+
+        # Database
+        self.database_path = os.environ.get("DATABASE_PATH", "deals.db")
+
+    @staticmethod
+    def _require(name: str) -> str:
+        value = os.environ.get(name)
+        if not value:
+            raise ValueError(f"Required environment variable {name} is not set")
+        return value