Mises à jour automatiques : image publiée sur ghcr.io via GitHub Actions + Watchtower

- Workflow build-image.yml : construit et pousse ghcr.io/r0m1k3/liveflow à
  chaque modification de app/
- Compose Unraid : image préconstruite au lieu du build local, service
  watchtower scopé par label pour redéployer l'app automatiquement

https://claude.ai/code/session_01YHMp3EKzr4s6o8w1ygxuUe

.github/workflows/build-image.yml

@@ -0,0 +1,35 @@
+name: Build & publish Docker image
+
+on:
+  push:
+    branches: ["main", "claude/**"]
+    paths: ["app/**", ".github/workflows/build-image.yml"]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-buildx-action@v3
+
+      - uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: ./app
+          push: true
+          tags: |
+            ghcr.io/r0m1k3/liveflow:latest
+            ghcr.io/r0m1k3/liveflow:${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max