Add a news review workflow and a staff notification area

News gains a PENDING_REVIEW status between draft and published. A
non-editor author (can_add_news but not can_publish_news -- a
coach_manager, not an ADMIN/EDITOR) gets a "Send for review" button
instead of Publish; an editor/admin always sees Publish directly, no
review step. Submitting notifies every ADMIN/EDITOR in-app only (see
notify_members' new send_email=False) -- a review queue that emailed
on every submission would get noisy fast.

The notification area itself: a topbar bell (badge + dropdown, same
<details>/<summary> convention as the sidebar's user-menu, generalised
to a shared .dismissable-details close handler) visible on every page,
plus a fuller "Notifications" card on the dashboard, both fed by a new
notification_bell context processor. "Mark all read" clears the
signed-in staff member's own unread notifications for this club.

This is the reusable notification system's first consumer beyond news
publishing itself -- validates that notify_members()/Notification
generalise the way they were meant to.

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

rosterchief/settings.py

@@ -204,6 +204,7 @@ TEMPLATES = [
                 "management.context_processors.news_permissions",
                 "management.context_processors.feature_sections",
                 "management.context_processors.sidebar_counters",
+                "management.context_processors.notification_bell",
             ],
         },
     },