Add Docker build workflow

.github/workflows/docker-build.yml

@@ -0,0 +1,101 @@
+# Docker Build - Build and push image to GitHub Container Registry
+#
+# This workflow builds the Docker image on every push to main
+# and pushes it to GitHub Container Registry (ghcr.io).
+#
+# Usage:
+# - Image is tagged with: latest, commit SHA, and Git tag (if present)
+# - Access packages at: https://github.com/OWNER/REPOSITORY/pkgs/container/REPO_NAME
+#
+# Required secrets:
+# - GITHUB_TOKEN (auto-provided): Used to authenticate with GHCR
+
+name: Docker Build
+
+on:
+    push:
+        branches: [main]
+        tags: ["v*"]
+    pull_request:
+        branches: [main]
+        paths:
+            - Dockerfile
+            - requirements.txt
+            - "**.py"
+    workflow_dispatch:
+        inputs:
+            tag:
+                description: "Custom tag for the image (optional)"
+                required: false
+                default: ""
+
+env:
+    REGISTRY: ghcr.io
+    IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        permissions:
+            contents: read
+            packages: write
+            attestations: write
+            id-token: write
+
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Set up Docker Buildx
+              uses: docker/setup-buildx-action@v3
+
+            - name: Log in to Container Registry
+              if: github.event_name != 'pull_request'
+              uses: docker/login-action@v3
+              with:
+                  registry: ${{ env.REGISTRY }}
+                  username: ${{ github.actor }}
+                  password: ${{ secrets.GITHUB_TOKEN }}
+
+            - name: Extract metadata
+              id: meta
+              uses: docker/metadata-action@v5
+              with:
+                  images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+                  tags: |
+                      type=ref,event=branch
+                      type=ref,event=pr
+                      type=semver,pattern={{version}}
+                      type=semver,pattern={{major}}.{{minor}}
+                      type=semver,pattern={{major}}
+                      type=sha,prefix=,suffix=,format=short
+                      type=raw,value=latest,enable={{is_default_branch}}
+                      type=raw,value=${{ inputs.tag }},enable=${{ inputs.tag != '' }}
+
+            - name: Build and push Docker image
+              id: push
+              uses: docker/build-push-action@v6
+              with:
+                  context: .
+                  push: ${{ github.event_name != 'pull_request' }}
+                  tags: ${{ steps.meta.outputs.tags }}
+                  labels: ${{ steps.meta.outputs.labels }}
+                  cache-from: type=gha
+                  cache-to: type=gha,mode=max
+                  platforms: linux/amd64,linux/arm64
+
+            - name: Generate artifact attestation
+              if: github.event_name != 'pull_request'
+              uses: actions/attest-build-provenance@v2
+              with:
+                  subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+                  subject-digest: ${{ steps.push.outputs.digest }}
+                  push-to-registry: true
+
+            - name: Print image digest
+              if: github.event_name != 'pull_request'
+              run: |
+                  echo "✅ Image pushed successfully!"
+                  echo "📦 Digest: ${{ steps.push.outputs.digest }}"
+                  echo "🐳 Tags:"
+                  echo "${{ steps.meta.outputs.tags }}"