ci(docker): emit comma-separated image list for buildx 'outputs' name=

The 'outputs: type=image,name=...,push-by-digest=true' field is parsed as
CSV by buildx; passing the newline-separated multi-line images.outputs.list
broke the parser with 'extraneous or missing " in quoted-field'. Add a
'csv' sibling output that joins ghcr + optional dockerhub names with commas
on a single line, and use that in the jammy by-digest build step.

Author: M0Rf30

.github/workflows/docker.yml

@@ -108,11 +108,14 @@ jobs:
         id: images
         run: |
           IMAGES="${{ env.REGISTRY }}/${{ github.repository }}-${{ matrix.os }}"
+          CSV="$IMAGES"
           if [ -n "${{ secrets.DOCKER_USERNAME }}" ]; then
             IMAGES="$IMAGES
           ${{ secrets.DOCKER_USERNAME }}/yap-${{ matrix.os }}"
+            CSV="$CSV,${{ secrets.DOCKER_USERNAME }}/yap-${{ matrix.os }}"
           fi
           { echo "list<<EOF"; echo "$IMAGES"; echo "EOF"; } >> "$GITHUB_OUTPUT"
+          echo "csv=$CSV" >> "$GITHUB_OUTPUT"
 
       - name: 📋 Extract metadata
         id: meta
@@ -143,7 +146,9 @@ jobs:
           platforms: ${{ matrix.platform }}
           labels: ${{ steps.meta.outputs.labels }}
           # Push each platform by digest; the merge job assembles the manifest.
-          outputs: type=image,"name=${{ steps.images.outputs.list }}",push-by-digest=true,name-canonical=true,push=true
+          # IMPORTANT: name= must be a comma-separated list (single line). Using
+          # the newline-separated images.outputs.list breaks buildx's CSV parser.
+          outputs: type=image,"name=${{ steps.images.outputs.csv }}",push-by-digest=true,name-canonical=true,push=true
           cache-from: type=gha,scope=${{ matrix.os }}-${{ matrix.platform }}
           cache-to: type=gha,mode=max,scope=${{ matrix.os }}-${{ matrix.platform }}
           build-args: |