issue-facade was renamed to issue-core. Update the dependency
declaration and the three Python imports it touched. Model field
names (issue_facade_backend, issue_facade_id) and the Django setting
ISSUE_FACADE_LOCAL_DB stay as-is — they are persisted/semantic
identifiers, not part of the package wiring.
All 20 aufgaben tests pass after the rewire.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>