Fix the bottom tab bar never actually highlighting the active screen

active_tab/screen_title were set as class attributes on every screen view,
but only ever threaded into the template context by _PlaceholderScreen's
own get_context_data -- which no real M1-M7 screen has inherited from
since each one got its own concrete implementation. Every screen's own
get_context_data override skipped them, so `active_tab` was always
undefined in the template and the tab bar never lit up. Defaulted both
from the class attributes in PersonScopeMixin (every screen's shared
base) via kwargs.setdefault, so a screen with its own dynamic
screen_title (EventDetailView's event.title) still wins.

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

mobile/mixins.py

@@ -73,6 +73,16 @@ class PersonScopeMixin(ClubScopedPublicMixin):
         if self.managed_people:
             unread_notification_count = Notification.objects.filter(club=self.request.club, member__in=self.managed_people, read_at__isnull=True).count()
 
+        # Every screen sets these as class attributes (see e.g. HomeView.active_tab),
+        # but only a subclass that explicitly forwards them into its own
+        # get_context_data actually gets them into the template -- easy to forget
+        # (most screens' own get_context_data never touch either one), so default
+        # them here instead. setdefault, not an outright override: a screen with a
+        # dynamic title (EventDetailView's event.title) already passes its own
+        # screen_title through kwargs, and that must win.
+        kwargs.setdefault("active_tab", getattr(self, "active_tab", ""))
+        kwargs.setdefault("screen_title", getattr(self, "screen_title", ""))
+
         return super().get_context_data(
             me=self.me,
             managed_people=self.managed_people,