ci: workflow Gitea de build et publication de l'image Docker

Build de l'image unique depuis backend.Dockerfile et push vers le
registre (secrets REGISTRY_*). Déclenché sur main, tags v* et manuel.
Tags d'image : latest/main sur la branche par défaut, semver
(X.Y.Z / X.Y / X) sur les tags. Pas de tag par SHA (économie d'espace
registre).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/docker-publish.yml

@@ -0,0 +1,82 @@
+name: Build and Publish Docker Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*"
+  workflow_dispatch:
+
+env:
+  REGISTRY: ${{ secrets.REGISTRY_URL }}
+  NAMESPACE: ${{ secrets.REGISTRY_NAMESPACE }}
+
+jobs:
+  build:
+    name: Build App Image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ secrets.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.NAMESPACE }}/plesna-gerance
+          tags: |
+            type=ref,event=branch
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=raw,value=latest,enable={{is_default_branch}}
+          labels: |
+            org.opencontainers.image.title=Plesna Gerance
+            org.opencontainers.image.description=Extracteur de comptes rendus de gerance Oralia/ICS (API + interface web)
+            org.opencontainers.image.source=${{ gitea.server_url }}/${{ gitea.repository }}
+            org.opencontainers.image.version=${{ gitea.ref_name }}
+
+      - name: Build and push image
+        id: build
+        uses: docker/build-push-action@v5
+        with:
+          # Conteneur unique : l'image builde le frontend Vue puis le fait
+          # servir par le backend FastAPI (cf. backend.Dockerfile).
+          context: .
+          file: ./backend.Dockerfile
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          platforms: linux/amd64
+
+      - name: Image digest
+        run: |
+          echo "Image pushed with digest: ${{ steps.build.outputs.digest }}"
+          echo "Tags: ${{ steps.meta.outputs.tags }}"
+
+  summary:
+    name: Build Summary
+    runs-on: ubuntu-latest
+    needs: [build]
+    if: always()
+    steps:
+      - name: Build summary
+        run: |
+          echo "## 🐳 Docker Image Built Successfully"
+          echo ""
+          echo "- Registry: ${{ env.REGISTRY }}/${{ env.NAMESPACE }}/plesna-gerance"
+          echo "- Tags: latest, ${{ gitea.ref_name }}"
+          echo ""
+          echo "### 🚀 Deployment"
+          echo "docker compose up -d"