Adds GET /api/v2/promotions/admin/promotions/ and .../referrals/, listing
every Promotion (type derived from Plan.processor) and referral activity
(invited_by = resolved payee, invited_user = raw event.data['user'] --
there's no dedicated referral model or referral_code field in this
codebase). Follows the existing _user/_application file-suffix convention
with a new _admin suffix, backed by real django-filter FilterSets.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
