[FR] Add CI workflow to build and push Docker image to GHCR

[rizlas]

Currently a CI workflow to automatically build and push our Docker image to ghcr.io is missing. This workflow should handle image publishing for both releases and development builds.

• Workflow should:

  • Trigger on:

    • Release creation → build and push image tagged with the release name
    • Push to development branch → build and push image tagged as latest
    • Manual trigger (workflow_dispatch) → build and push image tagged as latest

Example image tags:

• ghcr.io/bb-Ricardo/netbox-sync:v1.0.0 (for releases)
• ghcr.io/bb-Ricardo/netbox-sync:latest (for development)

I'd like to contribute this feature as discussed in #474 .