Add PayloadCMS service template

[285729101]

Summary

• Add a new service template for PayloadCMS, an open-source headless CMS and application framework built with Node.js and TypeScript
• Template includes PayloadCMS service (Node.js 20) with PostgreSQL database
• Adds PayloadCMS SVG logo and regenerates service template JSON files

Closes #2346

Details

• Image: node:20-alpine with create-payload-app bootstrapping on first run
• Database: PostgreSQL 16 (Alpine)
• Environment: Auto-generated secrets (SERVICE_PASSWORD_64_PAYLOADSECRET), database credentials, and public URL
• Health check: Checks /admin endpoint availability
• Volumes: Persistent storage for app data and PostgreSQL data

Test plan

• Deploy the PayloadCMS service template in Coolify
• Verify first-run initialization completes (project scaffolding, npm install, build)
• Verify the admin panel is accessible at /admin
• Verify PostgreSQL connection works correctly
• Verify persistent data survives container restart

🤖 Generated with Claude Code

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