refactor: replace Docker build steps with silta-actions/build-push-im… #3

	---
	name: Build & Push Images

	on:
	push:
	branches: ["**"]
	paths-ignore:
	- "k8s/**"
	- "**.md"
	pull_request:
	types: [opened, synchronize, reopened]

	concurrency:
	group: ${{ github.workflow }}-${{ github.event.pull_request.number \|\| github.ref }}
	cancel-in-progress: true

	env:
	REGISTRY: ${{ vars.REGISTRY \|\| 'registry.wdr.io' }}
	REPO: ${{ github.event.repository.name }}

	jobs:
	# ---------------------------------------------------------------
	# Stage 1: Validate codebase.
	# Simple project has no application code to lint — just verify
	# the Dockerfile and static content are well-formed.
	# ---------------------------------------------------------------
	validate:
	name: Validate
	runs-on: ubuntu-latest
	steps:
	- name: Checkout repository
	uses: actions/checkout@v4

	- name: Lint Dockerfile
	uses: hadolint/hadolint-action@v3.1.0
	with:
	dockerfile: silta/nginx.Dockerfile
	failure-threshold: error

	# ---------------------------------------------------------------
	# Stage 2: Build and push Docker image.
	# ---------------------------------------------------------------
	build-image:
	name: Build & Push — nginx
	runs-on: ubuntu-latest
	needs: validate
	permissions:
	contents: read

	steps:
	- name: Checkout repository
	uses: actions/checkout@v4

	- name: Build & push image
	uses: wunderio/silta-actions/build-push-image@v1
	with:
	image-name: nginx
	dockerfile: silta/nginx.Dockerfile
	registry: ${{ env.REGISTRY }}
	registry-username: ${{ secrets.REGISTRY_USERNAME }}
	registry-password: ${{ secrets.REGISTRY_PASSWORD }}

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