Fix: Only push Docker images on main branch pushes (#31)

* Initial plan

* Fix: Only push Docker images on main branch pushes

- Add conditional logic to frontend and backend build jobs
- Images are built for all branches but only pushed on main branch pushes
- Prevents image publishing on pull requests and other events

Co-authored-by: darthkali <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: darthkali <[email protected]>

Author: Copilot

.github/workflows/build-and-push.yaml

@@ -49,7 +49,7 @@ jobs:
           file: frontend/Dockerfile
           build-args: |
             VERSION=${{ env.VERSION }}
-          push: true
+          push: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
           tags: |
             ${{ env.RAG_EVAL_UI_IMAGE }}:${{ env.SHORT_SHA }}
             ${{ github.ref_type == 'tag' &&
@@ -98,7 +98,7 @@ jobs:
           file: backend/Dockerfile
           build-args: |
             VERSION=${{ env.VERSION }}
-          push: true
+          push: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}
           tags: |
             ${{ env.LLM_EVAL_BACKEND_IMAGE }}:${{ env.SHORT_SHA }}
             ${{ github.ref_type == 'tag' &&