fix: use Docker CLI with host daemon instead of buildah

- buildah requires user namespaces which aren't available in containers
- Use Docker CLI with host's Docker socket (already mounted by runner)
- Keep Alpine base and optimizations (git clone, sh shell)
- Simplest solution for containerized Kubernetes runners

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

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

.gitea/workflows/build.yaml

@@ -15,7 +15,7 @@ jobs:
       - name: Install dependencies
         shell: sh
         run: |
-          apk add --no-cache git buildah fuse-overlayfs
+          apk add --no-cache git docker-cli
 
       - name: Checkout code
         shell: sh
@@ -68,21 +68,21 @@ jobs:
       - name: Login to registry
         shell: sh
         run: |
-          echo "${{ secrets.PERSONAL_TOKEN }}" | buildah login --username "${{ gitea.actor }}" --password-stdin gitea.leeworks.dev
+          echo "${{ secrets.PERSONAL_TOKEN }}" | docker login gitea.leeworks.dev -u "${{ gitea.actor }}" --password-stdin
 
-      - name: Build and push with buildah
+      - name: Build and push with Docker
         shell: sh
         run: |
-          echo "Building image with buildah..."
-          buildah bud -t ${{ steps.tags.outputs.IMAGE_TAG }} .
+          echo "Building image..."
+          docker build -t ${{ steps.tags.outputs.IMAGE_TAG }} .
 
           echo "Pushing image..."
-          buildah push ${{ steps.tags.outputs.IMAGE_TAG }}
+          docker push ${{ steps.tags.outputs.IMAGE_TAG }}
 
           if [ "${{ steps.tags.outputs.PUSH_LATEST }}" = "true" ]; then
             echo "Tagging and pushing latest..."
-            buildah tag ${{ steps.tags.outputs.IMAGE_TAG }} ${{ steps.tags.outputs.IMAGE_LATEST }}
-            buildah push ${{ steps.tags.outputs.IMAGE_LATEST }}
+            docker tag ${{ steps.tags.outputs.IMAGE_TAG }} ${{ steps.tags.outputs.IMAGE_LATEST }}
+            docker push ${{ steps.tags.outputs.IMAGE_LATEST }}
           fi
 
           echo "Build and push completed successfully!"