Add Coach mode C6: bulk-add players to the active team's roster

management.forms.TeamMembershipForm is shaped for one member at a time
(per-row jersey number/position/captain flags), which doesn't fit a "tap a
few names, add them" flow -- the design mock itself shows plain checkboxes,
no inline position picker. Reuses the same two eligibility rules the form
applies internally (teams.services.eligible_roster_members, minus whoever's
already on this team+season) directly instead, and lets a coach fill in
jersey number/position afterward on the desktop -- the model's own
help_text already documents a blank position as a normal, expected state.

"Suggested" (on this team last season) is real, computed data via
club.models.Season.before. "Age eligible" from the mock isn't built --
neither Club nor Team carries an age-group field to compare a birth date
against, so faking that filter would just mean it silently matched nothing.

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

mobile/urls.py

@@ -27,4 +27,5 @@ urlpatterns = [
     path("coach/attendance/<uuid:event_id>/", coach_views.CoachAttendanceView.as_view(), name="coach_attendance"),
     path("coach/events/new/", coach_views.CoachCreateEventView.as_view(), name="coach_create_event"),
     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"),
 ]