Add a news app: coach_manager authoring, team tagging, photos, editor release flow

News and NewsPhoto (team-tagged instead of categorised, one photo taggable
as main via a partial unique constraint), gated per club/services/access.py:
any current-season coach_manager, EDITOR, or ADMIN can draft and edit a news
item; only EDITOR/ADMIN can publish it, or edit it once it's live. Publishing
takes a date so it can be scheduled ahead of time rather than only right now.

Authoring/release only for now -- no member-facing reading page or public API
yet, the visibility field (internal/external/both) is there for when those land.

rosterchief/settings.py

@@ -66,6 +66,7 @@ INSTALLED_APPS = [
     "members.apps.MembersConfig",
     "teams.apps.TeamsConfig",
     "events.apps.EventsConfig",
+    "news.apps.NewsConfig",
     "formbuilder.apps.FormbuilderConfig",
     "shop.apps.ShopConfig",
     # Platform billing: RosterChief charging the clubs. Not tenant data — see billing/models.py.
@@ -189,6 +190,7 @@ TEMPLATES = [
                 "management.context_processors.is_admin",
                 "management.context_processors.management_link",
                 "management.context_processors.active_nav_section",
+                "management.context_processors.news_permissions",
             ],
         },
     },