feat: add GET /version endpoint.

[LaGodxy]

Summary

Adds a simple endpoint to return the current API version of the backend service.

Problem

There is currently no straightforward way to verify which version of the API is deployed. This makes debugging, monitoring deployments, and verifying environment versions more difficult.

Scope

• Create a GET /version endpoint.

• Return a JSON response containing:

  • the service name
  • the current API version

Files Changed

• stellarspend-backend/src/app.controller.ts
• stellarspend-backend/src/app.service.ts

Acceptance Criteria

• The endpoint returns HTTP 200.
• The response format should be:

{
  "service": "stellarspend-api",
  "version": "1.0.0"
}

Labels

feature backend api simple

How to Test

1. Start the backend server.
2. Send a GET request to:

/version

3. Verify the response returns:

{
  "service": "stellarspend-api",
  "version": "1.0.0"
}

closes #59

[Uyoxy]

@LaGodxy kindly resolve your conflict