ci(workflows): rename output variable matrix to image_list

The variable name `matrix` in the `detect-changes` job output was ambiguous and potentially confusing, as `matrix` is a reserved keyword in Gitea/GitHub Actions syntax for defining job strategies.

This change renames the output variable to `image_list` to better reflect its content (a JSON array of image names) and avoid naming conflicts or confusion with the actual `strategy.matrix` configuration.

Changes:
- Renamed output `matrix` to `image_list` in `detect-changes` job.
- Updated all shell script references in the change detection logic.
- Updated the consumer job `build-push-images` to use `needs.detect-changes.outputs.image_list`.

.gitea/workflows/build-images.yml

@@ -23,7 +23,7 @@ jobs:
     container:
       image: alpine:3.20
     outputs:
-      matrix: ${{ steps.changes.outputs.matrix }}
+      image_list: ${{ steps.changes.outputs.image_list }}
       has_changes: ${{ steps.changes.outputs.has_changes }}
     steps:
       - name: Install dependencies
@@ -49,20 +49,20 @@ jobs:
               if [ -d "images/$IMAGE" ] && [ -f "images/$IMAGE/Dockerfile" ]; then
                  echo "DEBUG: Image directory and Dockerfile exist."
                  # Use printf for safer output
-                 printf "matrix=[\"%s\"]\n" "$IMAGE" >> $GITHUB_OUTPUT
+                 printf "image_list=[\"%s\"]\n" "$IMAGE" >> $GITHUB_OUTPUT
                  echo "has_changes=true" >> $GITHUB_OUTPUT
-                 echo "DEBUG: Set matrix=['$IMAGE']"
+                 echo "DEBUG: Set image_list=['$IMAGE']"
                  exit 0
               else
                  echo "Error: Image '$IMAGE' not found or missing Dockerfile at images/$IMAGE/Dockerfile"
                  echo "has_changes=false" >> $GITHUB_OUTPUT
-                 echo "matrix=[]" >> $GITHUB_OUTPUT
+                 echo "image_list=[]" >> $GITHUB_OUTPUT
                  exit 0
               fi
             else
                echo "DEBUG: Input image name was empty after trimming."
                echo "has_changes=false" >> $GITHUB_OUTPUT
-               echo "matrix=[]" >> $GITHUB_OUTPUT
+               echo "image_list=[]" >> $GITHUB_OUTPUT
                exit 0
             fi
           fi
@@ -84,18 +84,18 @@ jobs:
           if [ ! -s valid_images.txt ]; then
              echo "No valid images detected."
              echo "has_changes=false" >> $GITHUB_OUTPUT
-             echo "matrix=[]" >> $GITHUB_OUTPUT
+             echo "image_list=[]" >> $GITHUB_OUTPUT
           else
              # Convert list to JSON array using jq
              JSON=$(cat valid_images.txt | jq -R -s -c 'split("\n") | map(select(length > 0))')
              echo "Detected images: $JSON"
-             echo "matrix=$JSON" >> $GITHUB_OUTPUT
+             echo "image_list=$JSON" >> $GITHUB_OUTPUT
              echo "has_changes=true" >> $GITHUB_OUTPUT
           fi
 
       - name: Show detected changes
         run: |
-          echo "Matrix: ${{ steps.changes.outputs.matrix }}"
+          echo "Image List: ${{ steps.changes.outputs.image_list }}"
           echo "Has changes: ${{ steps.changes.outputs.has_changes }}"
 
   # ============================================================================
@@ -109,7 +109,7 @@ jobs:
       image: docker:cli
     strategy:
       matrix:
-        image: ${{ fromJson(needs.detect-changes.outputs.matrix) }}
+        image: ${{ fromJson(needs.detect-changes.outputs.image_list) }}
       fail-fast: false
     steps:
       - name: Install dependencies