fix(tenancy): use absolute URL in team invitation email link

Email clients need absolute URLs to make links clickable. The
acceptance_link was a relative path (/store/invitation/accept?token=...)
which rendered as plain text. Now prepends the platform domain with
the correct protocol.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/prospecting/routes/api/admin_campaigns.py

@@ -99,7 +99,7 @@ def send_campaign(
         db,
         template_id=data.template_id,
         prospect_ids=data.prospect_ids,
-        sent_by_user_id=current_admin.user_id,
+        sent_by_user_id=current_admin.id,
     )
     db.commit()
     return [CampaignSendResponse.model_validate(s) for s in sends]