fix: remove broken request-id middleware with invalid Go template (refs #103)

The request-id middleware used {{ .Request.Host }} which is not available
at config load time in the file provider. This template error blocked
the entire file provider from loading, preventing all file-based
middlewares (including grafana-ipwhitelist) from being registered.

The middleware was unused (not referenced by any router or chain) and
the backend already generates X-Request-Id via randomUUID().

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

config/traefik/dynamic/middleware.yml

@@ -1,16 +1,5 @@
 http:
   middlewares:
-    # Request ID forwarding middleware
-    # Note: Traefik v3 lacks native UUID generation
-    # Backend generates X-Request-Id if not present in request
-    # This middleware ensures the header is forwarded when present
-    request-id:
-      headers:
-        customRequestHeaders:
-          X-Forwarded-Host: "{{ .Request.Host }}"
-        # X-Request-Id forwarded automatically via passthrough
-        # Backend responsibility: generate UUID if header missing
-
     # Security headers middleware
     secure-headers:
       headers: