feat(server): add keep-alive ping to prevent PaaS services from sleeping

[devin-ai-integration]

📋 Description

Adds a configurable keep-alive ping mechanism that periodically hits URLs to prevent PaaS free-tier services (Render, Railway, etc.) from going idle/sleeping.

When enabled, the server will:

1. Ping its own SERVER_URL automatically
2. Ping any additional URLs listed in KEEP_ALIVE_URLS (e.g. a BotWave deployment)

Configuration (env vars)

Variable	Default	Description
KEEP_ALIVE_ENABLED	false	Enable/disable keep-alive pings
KEEP_ALIVE_INTERVAL	10	Ping interval in minutes
KEEP_ALIVE_URLS	(empty)	Comma-separated external URLs to ping

Example usage on Render

KEEP_ALIVE_ENABLED=true
KEEP_ALIVE_INTERVAL=10
KEEP_ALIVE_URLS=https://your-botwave-app.onrender.com
SERVER_URL=https://your-evolution-api.onrender.com

🧪 Type of Change

• ✨ New feature (non-breaking change which adds functionality)

🧪 Testing

• Manual testing completed
• TypeScript compilation passes (tsc --noEmit)
• ESLint passes (npm run lint:check)
• No breaking changes introduced — disabled by default

✅ Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have manually tested my changes thoroughly
• I have verified the changes work with different scenarios
• Any dependent changes have been merged and published

Link to Devin session: https://app.devin.ai/sessions/812442be799c4cd59ca9c40eee75263b
Requested by: @eksucampusmarketplace-cell

[devin-ai-integration]

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