Store and display sender's WhatsApp name

Use pushName from baileys to get the sender's display name instead
of just the phone number. Falls back to phone number if no name.

Includes migration to add sender_name column to existing databases.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/index.ts

@@ -95,8 +95,7 @@ async function processMessage(msg: NewMessage): Promise<void> {
   // Build prompt with conversation history
   const lines = missedMessages.map(m => {
     const time = new Date(m.timestamp).toLocaleTimeString();
-    const sender = m.sender.split('@')[0];
-    return `[${time}] ${sender}: ${m.content}`;
+    return `[${time}] ${m.sender_name}: ${m.content}`;
   });
   const prompt = lines.join('\n');
 
@@ -213,7 +212,7 @@ async function connectWhatsApp(): Promise<void> {
       if (!msg.message) continue;
       const chatJid = msg.key.remoteJid;
       if (!chatJid || chatJid === 'status@broadcast') continue;
-      storeMessage(msg, chatJid, msg.key.fromMe || false);
+      storeMessage(msg, chatJid, msg.key.fromMe || false, msg.pushName || undefined);
     }
   });
 }