[feat] add coolify-node entity and example

[MaksymTrykur]

This pull request introduces a new "Coolify" integration, enabling the deployment and management of self-hosted Coolify instances using Monk. The changes include configuration files, a detailed example, and a custom lifecycle script for managing nodes. Below are the most important changes grouped by theme:

Configuration and Manifest Setup:

• Added a MANIFEST file to define the repository, load a YAML schema, and reference the lifecycle script (node-sync.js).
• Introduced example.yaml to define a namespace, root-node and join-node configurations, and a stack setup for deploying Coolify instances. This file also specifies Azure as the provider and includes secrets management.

Documentation:

• Created a README.md file with a usage example for setting up Coolify instances, including commands for loading the manifest, setting secrets, and running the stack. It also provides instructions for accessing the deployed instance.

Schema Definition:

• Added node-entity.yaml, which defines the schema for a Coolify node, including required properties (e.g., provider, region, instance) and lifecycle management using the custom sync script.

Lifecycle Management:

• Implemented node-sync.js, a lifecycle script that handles creating, updating, and deleting nodes. It includes logic for root-node initialization, API token generation, and joining additional nodes to the root instance. The script also manages SSH keys and validates nodes against the Coolify API.