feat: Implement short SHA for backend image tagging and deployment, and refine image tag resolution for pull requests.

.forgejo/workflows/deploy-backend.yaml

@@ -16,7 +16,7 @@ env:
 
   # Docker Image
   BACKEND_IMAGE_NAME: chamomind/elearning-backend
-  IMAGE_TAG: ${{ github.sha }}
+  IMAGE_TAG: ${{ github.event.pull_request.head.sha || github.sha }}
 
   # Notifications
   DISCORD_WEBHOOK_URL: ${{ vars.DISCORD_WEBHOOK_URL }}
@@ -25,10 +25,16 @@ jobs:
   build:
     name: Build Backend Docker Image
     runs-on: ubuntu-latest
+    outputs:
+      short_sha: ${{ steps.vars.outputs.short_sha }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
 
+      - name: Generate short SHA
+        id: vars
+        run: echo "short_sha=$(echo ${{ github.sha }} | cut -c1-7)" >> $GITHUB_OUTPUT
+
       - name: Log in to Container Registry
         uses: docker/login-action@v3
         with:
@@ -48,7 +54,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ${{ env.REGISTRY }}/${{ env.BACKEND_IMAGE_NAME }}:${{ env.IMAGE_TAG }}
+          images: ${{ env.REGISTRY }}/${{ env.BACKEND_IMAGE_NAME }}
           tags: |
             type=ref,event=branch
             type=sha,prefix=
@@ -80,7 +86,7 @@ jobs:
           script: |
             cd ~/repo
             chmod +x ./replace-env.sh ./deploy.sh
-            ./replace-env.sh BACKEND_TAG "${{  env.IMAGE_TAG }}"
+            ./replace-env.sh BACKEND_TAG "${{ needs.build.outputs.short_sha }}"
             ./deploy.sh backend
 
   notify: