fix: move Sablier middleware to dynamic configuration

Moved Sablier middleware from Docker labels to Traefik dynamic configuration
to fix "unknown plugin type: sablier" error. Traefik plugins can only be
used in dynamic file configuration, not in Docker labels.

Changes:
- Removed sablier-vert@file reference from Docker label middleware chain
- Added complete router definition to proxy/dynamic/vert-sablier.yaml
- Router includes full middleware chain: sablier-vert → vert-auth → compress
- Kept sablier.enable and sablier.group labels for Sablier service discovery

This allows Sablier to properly scale the container to zero while maintaining
the middleware chain order through file-based configuration.

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

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

proxy/dynamic/vert-sablier.yaml

@@ -9,3 +9,16 @@ http:
           dynamic:
             displayName: VERT File Converter
             theme: ghost
+
+  routers:
+    vert-web-secure:
+      rule: "Host(`vert.pivoine.art`)"
+      service: vert@docker
+      entryPoints:
+        - web-secure
+      middlewares:
+        - sablier-vert
+        - vert-auth@docker
+        - vert-web-secure-compress@docker
+      tls:
+        certResolver: resolver