fix: standardize poimen-workflows CI to unified pattern (#5)

Unified pattern enforced:
- test job: runs on all branches + PRs
- build-push job: only on main push, depends on test
- Proper env vars (GOPRIVATE, REGISTRY, IMAGE)
- Install Node.js before checkout
- Install docker only in build-push
- Docker login + build + push + prune

---------

Co-authored-by: Test <[email protected]>
Reviewed-on: #5

.gitea/workflows/ci.yaml

@@ -41,14 +41,18 @@ jobs:
     runs-on: golang
     steps:
       - name: Install Node.js and Docker
-        run: apt-get update && apt-get install -y nodejs docker.io
+        run: |
+          apt-get update
+          apt-get install -y nodejs docker.io
 
       - name: Checkout code
         uses: actions/checkout@v4
 
       - name: Get short SHA
         id: sha
-        run: echo "short_sha=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT
+        run: |
+          SHORT_SHA=$(git rev-parse --short HEAD)
+          echo "short_sha=${SHORT_SHA}" >> $GITHUB_OUTPUT
 
       - name: Registry login
         run: |
@@ -58,7 +62,7 @@ jobs:
           REGISTRY_USER: ${{ secrets.FORGEJO_REGISTRY_USER }}
           REGISTRY_TOKEN: ${{ secrets.FORGEJO_REGISTRY_TOKEN }}
 
-      - name: Build and push image
+      - name: Build Docker image
         run: |
           docker build --no-cache \
             -t "${IMAGE}:${{ steps.sha.outputs.short_sha }}" \