Fix reaction clap-backs replying to the bot's own message

Send as a channel message instead of message.reply() so it doesn't
look like the bot is talking to itself.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cogs/chat.py

@@ -302,7 +302,7 @@ class ChatCog(commands.Cog):
 
         self._chat_history[ch_id].append({"role": "assistant", "content": response})
 
-        await message.reply(response, mention_author=False)
+        await channel.send(response)
         logger.info(
             "Reaction reply in #%s to %s (%s): %s",
             channel.name,