Add billing-ending banner, events CRUD, RBIHF import, public API, team photos, and sponsors

A large batch of club-management features built up over one session:

- Club dashboard banner warning admins 1 month before billing ends
- Full Events/EventSeries CRUD (recurrence builder, occurrence lifecycle,
  per-team permissions), with match->game rename and game-specific fields
  (score, competition, live status, external game ID)
- Django-admin competition dropdown, gated per-club by feature flag
- Auto-import of RBIHF fixtures (scrape -> diff -> preview -> confirm),
  with location/opponent dropdowns suggested from existing club data
- Feature-flag-gated Shop/Forms nav sections, reusing the same flag
  machinery for the RBIHF import button
- Team roster now scoped to members active this season or next, sorted and
  grouped by position
- Club sport type (ice hockey / other), shown in the control panel's club
  subtitle
- Per-season team photo upload from the team page
- New public read-only API (Django Ninja) at /api/v1/: news, team rosters,
  upcoming/live/per-team games, and sponsors -- auto-documented via Swagger
  UI, CORS-enabled for a club's own external website
- Club sponsors: admin-only CRUD (logo, URL, active date window) plus a
  date-windowed, optionally randomized API endpoint
- Assorted fixes: NullBooleanField dropdown rendering, cross-club event
  validation timing, searchable-select chip placement, btn-neutral ->
  default button style sweep, calendar-month chart windows

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01R1gj3J1QPfP38XWpnpbFpy

rosterchief/settings.py

@@ -78,6 +78,8 @@ INSTALLED_APPS = [
     # Club-facing UI for team managers, coaches and admins -- not controlpanel (platform
     # staff managing every club) and not the future parent/player app.
     "management.apps.ManagementConfig",
+    # Public, read-only JSON API for a club's own external website -- see api/urls.py.
+    "api.apps.ApiConfig",
 ]
 
 # Feature flags (django-waffle). The Flag model is swappable, like AUTH_USER_MODEL:
@@ -100,6 +102,9 @@ MIDDLEWARE = [
     "club.tenancy.ClubTenantMiddleware",
     # After tenancy: it decides club-vs-platform from request.club, which was just resolved.
     "features.middleware.MaintenanceMiddleware",
+    # After maintenance: a club under maintenance closes its public API too, same as
+    # everything else on its subdomain.
+    "api.middleware.PublicApiCorsMiddleware",
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
 ]
@@ -193,6 +198,7 @@ TEMPLATES = [
                 "management.context_processors.management_link",
                 "management.context_processors.active_nav_section",
                 "management.context_processors.news_permissions",
+                "management.context_processors.feature_sections",
             ],
         },
     },