feat: add afterthoughts, memory callbacks, and callback-worthy extraction

Add triple-pipe afterthought splitting to chat replies so the bot can
send a follow-up message 2-5 seconds later, mimicking natural Discord
typing behavior. Update all 6 personality prompts with afterthought
instructions (~1 in 5 replies) and memory callback guidance so the bot
actively references what it knows about users. Enhance memory extraction
prompt to flag bold claims, contradictions, and embarrassing moments as
high-importance callback-worthy memories with a "callback" topic tag.

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

cogs/chat.py

@@ -415,7 +415,22 @@ class ChatCog(commands.Cog):
                 except (asyncio.TimeoutError, asyncio.CancelledError):
                     pass
 
-        await message.reply(response, mention_author=False)
+        # Split afterthoughts (triple-pipe delimiter)
+        main_reply = response
+        afterthought = None
+        if "|||" in response:
+            parts = response.split("|||", 1)
+            main_reply = parts[0].strip()
+            afterthought = parts[1].strip() if len(parts) > 1 else None
+            if not main_reply:
+                main_reply = response
+                afterthought = None
+
+        await message.reply(main_reply, mention_author=False)
+
+        if afterthought:
+            await asyncio.sleep(random.uniform(2.0, 5.0))
+            await message.channel.send(afterthought)
 
         # Fire-and-forget memory extraction
         if not image_attachment: