feat: initial implementation — Arte Concert web GUI

FastAPI backend + HTML/JS frontend pour parcourir et télécharger les
concerts Arte Concert. Cache 6h, recherche live, historique SQLite,
suivi de progression SSE, design sombre Playfair Display + Inter.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/docker.yml

@@ -0,0 +1,38 @@
+name: Docker
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install docker CLI
+        run: |
+          apt-get update -qq && apt-get install -y -qq ca-certificates curl gnupg
+          install -m 0755 -d /etc/apt/keyrings
+          curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+          echo "deb [arch=amd64 signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/debian bullseye stable" > /etc/apt/sources.list.d/docker.list
+          apt-get update -qq && apt-get install -y -qq docker-ce-cli
+
+      - uses: actions/checkout@v3
+
+      - uses: docker/setup-buildx-action@v2
+        with:
+          driver: docker
+
+      - uses: docker/login-action@v2
+        with:
+          registry: forge.dilain.com
+          username: laurent
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
+      - name: Build & push
+        run: |
+          docker build \
+            -t forge.dilain.com/laurent/arte-dl:main \
+            -t forge.dilain.com/laurent/arte-dl:latest \
+            .
+          docker push forge.dilain.com/laurent/arte-dl:main
+          docker push forge.dilain.com/laurent/arte-dl:latest