Simplify the line-up to yes/no picks, and stop truncating notifications

Coach mode's line-up screen no longer has lines/slots -- just a yes/no
toggle per available roster player, grouped by their roster position, both
in coach mode and on the published member-side view. Replaces LineupUnit/
LineupSlot with a single LineupSelection model.

Notifications now show their full body text (no more truncatechars) and the
unread colour bar spans the full row height via self-stretch, matching the
calendar row's own marker, so it still reads correctly once a body wraps to
several lines.

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

mobile/urls.py

@@ -31,7 +31,5 @@ urlpatterns = [
     path("coach/news/new/", coach_views.CoachCreateNewsView.as_view(), name="coach_create_news"),
     path("coach/roster/add/", coach_views.CoachAddPlayerView.as_view(), name="coach_add_player"),
     path("coach/lineup/<uuid:event_id>/", coach_views.CoachLineupView.as_view(), name="coach_lineup"),
-    path("coach/lineup/<uuid:event_id>/units/add/", coach_views.CoachLineupAddUnitView.as_view(), name="coach_lineup_add_unit"),
-    path("coach/lineup/units/<uuid:unit_id>/slots/add/", coach_views.CoachLineupAddSlotView.as_view(), name="coach_lineup_add_slot"),
     path("coach/lineup/<uuid:event_id>/publish/", coach_views.CoachLineupPublishView.as_view(), name="coach_lineup_publish"),
 ]