feat: add Sablier v1.10.1 plugin for dynamic scaling

Added Sablier plugin and service for scale-to-zero capabilities:

**Traefik Plugin:**
- Added experimental.plugins.sablier configuration
- Plugin version: v1.10.1
- Module: github.com/acouvreur/sablier/plugins/traefik

**Sablier Service:**
- Created sablier/compose.yaml with Sablier server
- Uses Docker provider for container management
- Mounts Docker socket for container control
- Connected to falcon_network

**Configuration:**
- Added SABLIER_COMPOSE_PROJECT_NAME to arty.yml
- Added SABLIER_VERSION to arty.yml
- Included sablier stack in compose.yaml

**Usage:**
Services can now use Sablier middleware to automatically
scale to zero when idle and start on demand when accessed.

Example middleware configuration:
```yaml
http:
  middlewares:
    my-sablier:
      plugin:
        sablier:
          sablierUrl: http://sablier_app:10000
          names: service-name
          sessionDuration: 1m
```

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

sablier/compose.yaml

@@ -0,0 +1,21 @@
+services:
+  sablier:
+    image: acouvreur/sablier:${SABLIER_VERSION:-1.10.1}
+    container_name: ${SABLIER_COMPOSE_PROJECT_NAME}_app
+    restart: unless-stopped
+    command:
+      - start
+      - --provider.name=docker
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+    networks:
+      - compose_network
+    environment:
+      TZ: ${TIMEZONE:-Europe/Berlin}
+    labels:
+      - 'traefik.enable=false'
+
+networks:
+  compose_network:
+    name: ${NETWORK_NAME}
+    external: true