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/matrix_client.py

@@ -0,0 +1,51 @@
+"""Matrix client wrapper for sending deal messages."""
+
+import logging
+
+from nio import AsyncClient, RoomSendError
+
+logger = logging.getLogger(__name__)
+
+
+class MatrixDealsClient:
+    def __init__(
+        self,
+        homeserver_url: str,
+        user_id: str,
+        access_token: str,
+        room_id: str,
+    ):
+        self.room_id = room_id
+        self._client = AsyncClient(homeserver_url, user_id)
+        self._client.access_token = access_token
+        self._client.user_id = user_id
+
+    async def send_deal(self, plain_text: str, html: str) -> bool:
+        """Send a deal message to the configured room.
+
+        Returns True on success, False on failure.
+        """
+        content = {
+            "msgtype": "m.text",
+            "format": "org.matrix.custom.html",
+            "body": plain_text,
+            "formatted_body": html,
+        }
+
+        try:
+            resp = await self._client.room_send(
+                room_id=self.room_id,
+                message_type="m.room.message",
+                content=content,
+            )
+            if isinstance(resp, RoomSendError):
+                logger.error("Failed to send message: %s", resp.message)
+                return False
+            logger.debug("Message sent: %s", resp.event_id)
+            return True
+        except Exception as exc:
+            logger.error("Matrix send error: %s", exc)
+            return False
+
+    async def close(self):
+        await self._client.close()