Support env input as KEY=VALUE lines

.github/workflows/docker-build-publish.yml

@@ -19,6 +19,13 @@ on:
         type: string
         default: ""
 
+      env:
+        description: >
+          Multiline env vars, one per line: KEY=VALUE
+        required: false
+        type: string
+        default: ""
+
       trivy_severity:
         required: false
         type: string
@@ -44,6 +51,19 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Load env vars
+        if: ${{ inputs.env != '' }}
+        run: |
+          while IFS= read -r line; do
+            [ -z "$line" ] && continue
+            case "$line" in \#*) continue;; esac
+            if [[ "$line" != *=* ]]; then
+              echo "Invalid env line: $line" >&2
+              exit 1
+            fi
+            echo "$line" >> "$GITHUB_ENV"
+          done <<< "${{ inputs.env }}"
+
       - name: Start ssh-agent
         if: ${{ secrets.ssh_private_key != '' }}
         uses: webfactory/ssh-agent@v0.9.0