Set DOCKER_HOST explicitly in workflow

- Add env.DOCKER_HOST at workflow level
- Use host IP that DIND is exposed on
- Ensures all docker commands use TCP connection to DIND
- Shows DOCKER_HOST value in logs for debugging

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.forgejo/workflows/docker-build.yml

@@ -5,22 +5,18 @@ on:
     branches:
       - main
 
+env:
+  DOCKER_HOST: tcp://172.16.208.4:2375
+
 jobs:
   build-and-push:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Set up Docker (use runner's DOCKER_HOST)
+      - name: Set up Docker
         run: |
-          # The runner should have DOCKER_HOST set
+          echo "DOCKER_HOST: ${DOCKER_HOST}"
-          echo "DOCKER_HOST from runner: ${DOCKER_HOST:-not set}"
+          apt-get update -qq && apt-get install -y -qq docker.io
-
-          # Install docker client if not present
-          if ! command -v docker &> /dev/null; then
-            echo "Installing docker client..."
-            apt-get update -qq && apt-get install -y -qq docker.io
-          fi
-
           docker version
 
       - name: Checkout repository