After the Q3/2026 backfill the staff reported the Nachweise tab still
showed Q3 rows as "Offen" with no visual cue that a support payment had
been created. Reason: the existing columns only reflect Nachweis field
confirmations (Studiennachweis / income / assets), not the payment.
Add a small status badge next to the Nachweis status that links to the
related DestinataerUnterstuetzung when one exists. Colour follows the
payment lifecycle: blue when planned, info when proof submitted, warning
when released for payout, success when transferred.
Uses the existing VierteljahresNachweis.get_related_support_payment()
helper, so no model changes and no migration.
Refs STI-107
Co-Authored-By: Paperclip <noreply@paperclip.ing>
