Add sassy AI personality with mention detection

- Add utils/ai.js with NanoGPT integration for GLM-4.5-Air model
- Sassy system prompt: lowercase, slang, no emoji, opinionated gamer
- Conversation history per channel for context
- Update bot.js with messageCreate event for @mention responses
- Add NANO_MODEL env var for model selection

bot.js

@@ -14,6 +14,7 @@ import path from 'node:path';
 import { Client, Collection, Events, GatewayIntentBits } from 'discord.js';
 import Logger from './logger.js';
 import { loadCommands } from './utils/commandLoader.js';
+import { getAIResponse, isAIEnabled, clearHistory } from './utils/ai.js';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
@@ -40,6 +41,57 @@ client.once(Events.ClientReady, () => {
   logger.log(`Ready! Logged in as ${client.user.tag}`);
 });
 
+// Handle messages where the bot is mentioned
+client.on(Events.MessageCreate, async message => {
+  // Ignore bot messages
+  if (message.author.bot) return;
+
+  // Check if bot is mentioned
+  const botId = client.user.id;
+  const mentioned = message.mentions.has(botId);
+
+  if (!mentioned) return;
+
+  // Don't respond to commands (they start with /)
+  if (message.content.trim().startsWith('/')) return;
+
+  if (!isAIEnabled()) {
+    logger.warn('AI response requested but NANOGPT_API_KEY not set');
+    return;
+  }
+
+  try {
+    // Get the clean prompt (remove the bot mention)
+    const cleanPrompt = message.content
+      .replace(new RegExp(`<@!?${botId}>`, 'g'), '')
+      .trim();
+
+    if (!cleanPrompt) return;
+
+    // Get username of who mentioned us
+    const mentionedUsername = message.author.username;
+
+    logger.log(`Mentioned by ${mentionedUsername} in #${message.channel.name}: ${cleanPrompt.substring(0, 50)}...`);
+
+    // Typing indicator
+    await message.channel.sendTyping();
+
+    const response = await getAIResponse(cleanPrompt, message.channel.id, mentionedUsername);
+
+    // Send response (avoiding mention loop)
+    await message.reply({
+      content: response,
+      allowedMentions: { users: [] }, // Prevent mentioning the user back
+    });
+  } catch (error) {
+    logger.error('AI response failed:', error.message);
+    await message.reply({
+      content: 'lol damn, something broke. try again in a sec',
+      allowedMentions: { users: [] },
+    });
+  }
+});
+
 client.on(Events.InteractionCreate, async interaction => {
   if (!interaction.isChatInputCommand()) return;