feat: Import-Rollback fuer bestaetigte Auszuege (v0.3.0)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

finance/app/routers/imports.py

@@ -150,6 +150,25 @@ def confirm(statement_id: int, session: Session = Depends(get_session)):
     return StatementOut.model_validate(stmt)
 
 
+@router.post("/{statement_id}/rollback")
+def rollback(statement_id: int, session: Session = Depends(get_session)):
+    stmt = session.get(Statement, statement_id)
+    if stmt is None:
+        raise HTTPException(404, "Import nicht gefunden")
+    if stmt.status != "confirmed":
+        raise HTTPException(409, "Nur bestätigte Importe können zurückgerollt werden")
+    txs = session.execute(
+        select(Transaction).where(Transaction.statement_id == statement_id)
+    ).scalars().all()
+    deleted = len(txs)
+    for tx in txs:
+        session.delete(tx)
+    session.flush()
+    session.delete(stmt)
+    session.commit()
+    return {"deleted_transactions": deleted, "statement_id": statement_id}
+
+
 @router.delete("/{statement_id}", status_code=204)
 def delete_import(statement_id: int, session: Session = Depends(get_session)):
     stmt = session.get(Statement, statement_id)