Add a Payments & dues section to the Me page, matching the design's M5 row

Home already had the M1 dues card; Me's own "Payments & dues" row was
explicitly stubbed out with nowhere to lead. Give it a real destination:
a Payments screen (open balances for everyone managed, reusing Home's
dues-card layout via a shared _dues_row.html partial) and a "N OPEN"
pill on the Me row itself, only shown once something is actually owed.
club.services.fees.open_dues_rows is factored out so Home and Payments
can never drift apart on what counts as "still open".

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

mobile/urls.py

@@ -18,6 +18,7 @@ urlpatterns = [
     path("news/", views.NewsListView.as_view(), name="news_list"),
     path("news/<slug:slug>/", views.NewsDetailView.as_view(), name="news_detail"),
     path("me/", views.MeView.as_view(), name="me"),
+    path("me/payments/", views.PaymentsView.as_view(), name="payments"),
     path("me/calendar-sync/", views.CalendarFeedSettingsView.as_view(), name="calendar_feed_settings"),
     path("me/<uuid:member_id>/edit/", views.EditProfileView.as_view(), name="edit_profile"),
     path("notifications/", views.NotificationsView.as_view(), name="notifications"),