The 'Abgeschlossen' column was redundant after 'Überwiesen' since no further
action occurs after a payment is transferred. The pipeline is now 4 stages:
Offen → Nachweis eingereicht → Freigegeben → Überwiesen.
Existing 'abgeschlossen' records are merged into the 'Überwiesen' column.
Financial reports and queries are unaffected as they already include both statuses.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>