Implemented Connect API

[numair03]

Summary

Implemented the connect API for the co-ordination server.

What this PR does

• Adds ConnectHandler
• Analyzes and validates incoming JSON requests
• Verifies request method
• Validates required request fields (deviceId, isHealthy)
• Retrieves device configuration from a dummy in-memory database
• Returns GhostWire IP, WireGuard port, allowlist, and blocklist
• Returns appropriate HTTP status codes and JSON responses

Related issue

Closes #9

Component(s) touched

• Coordination server
• Clientside Agent (WireGuard / NAT / CLI)
• Desktop client (Frontend)
• Docs / infra

Testing

Tested using Postman. Test screenshots have been included in the PR.
Verified the following scenarios:

• Successful device connection (200 OK)
• Unknown device ID (404 Not Found)
• Missing required field deviceId (400 Bad Request)
• Device reported unhealthy (406 Not Acceptable)
• Invalid JSON body (400 Bad Request)

Checklist

• Tests added or updated for the change
• Tests passes locally
• Code follows style standards
• No unrelated files changed
• Docs/comments updated if behavior changed

Screenshots

200 OK

404 Not Found

400 Bad Request

406 Not Acceptable

400 Bad Request (Invalid JSON)