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

static/js/searchable-select.js

@@ -18,7 +18,7 @@
         wrapper.className = "relative";
 
         const chips = document.createElement("div");
-        chips.className = "flex flex-wrap gap-1 empty:hidden mb-3";
+        chips.className = "flex flex-wrap gap-1 empty:hidden mt-2";
 
         const input = document.createElement("input");
         input.type = "text";
@@ -31,7 +31,12 @@
 
         select.parentNode.insertBefore(wrapper, select);
         if (isMultiple) {
-            wrapper.append(chips, input, list, select);
+            // Chips render below the input, not above it: above meant every pick grew
+            // the block ahead of the input and shoved it (and your cursor) down --
+            // disorienting mid-search. Below, the input stays put; only the space
+            // beneath it grows, and the open dropdown (absolutely positioned right
+            // under the input) simply overlaps the chips while it's open.
+            wrapper.append(input, list, chips, select);
         } else {
             wrapper.append(input, list, select);
         }