WhatsApp API Server

API endpoints:

GET /api/qr/:sessionId - Get QR code for login
GET /api/status/:sessionId - Check connection status
POST /api/send - Send message (uses connection with lowest send count in last 24h)
Body: { "number": "1234567890", "message": "Hello" }
POST /api/send/:sessionId - Send message (specific session)
Body: { "number": "1234567890", "message": "Hello" }
GET /api/health - Health check for monitoring (uptime, session count)
POST /api/check-number - Check if number is registered on WhatsApp
Body: { "number": "6281234567890" }
POST /api/logout/:sessionId - Logout session
GET /api/sessions - List all sessions
GET /api/messages - Get messages with pagination & filters
Query params: page, limit, remoteJid, messageText, sessionId