fix(ci): install docker cli before building image in production workflow (#237)

Runner doesn't have docker pre-installed; explicitly install docker.io
matching the pattern used in microwaveprop.

Reviewed-on: graham/towerops-web#237

.forgejo/workflows/production.yaml

@@ -98,11 +98,14 @@ jobs:
           echo "tag=${TAG}" >> $GITHUB_OUTPUT
           echo "Full image tag: ${TAG}"
 
+      - name: Install Docker CLI
+        run: |
+          apt-get update && apt-get install -y docker.io
+
       - name: Build and push Docker image
         run: |
           IMAGE_TAG="${{ steps.tag.outputs.tag }}"
 
-          # Build using existing Docker daemon (runner user is in docker group)
           docker build \
             --build-arg MIX_ENV=prod \
             --file k8s/Dockerfile \