Add a placeholder Evaluations nav entry so the design doesn't get forgotten

Under Settings, next to Referee levels/Forms -- but deliberately not behind
a waffle Flag like the shop/forms stubs, since a flag-gated link disappears
from the nav entirely until someone remembers to turn it on, which defeats
the point of a standing reminder. Visible to MEMBER_ADMIN/ADMIN
unconditionally, links to a bare "coming soon" page (reuses
_generic_list.html with an empty object_list -- there's no model yet).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

management/urls.py

@@ -135,6 +135,8 @@ urlpatterns = [
     # Forms
     path("forms/", views.FormListView.as_view(), name="form_list"),
     path("forms/<uuid:pk>/submissions/", views.SubmissionListView.as_view(), name="submission_list"),
+    # Evaluations (placeholder -- see ARCHITECTURE.md §5.8, nothing built yet)
+    path("evaluations/", views.EvaluationsComingSoonView.as_view(), name="evaluations"),
     # Settings (admin only)
     path("settings/", views.ClubSettingsView.as_view(), name="club_settings"),
     path("settings/email-previews/<str:key>/render/", views.EmailPreviewRenderView.as_view(), name="email_preview_render"),