feat: Buchungen serverseitig nach Spalte sortierbar (A11-T5)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

finance/app/routers/gui.py

@@ -25,7 +25,7 @@ from app.routers.planning import list_planned as _list_planned
 from app.routers.planning import list_recurring as _list_recurring
 from app.routers.planning import recurring_suggestions as _recurring_suggestions
 from app.routers.scenarios import list_scenarios as _list_scenarios
-from app.routers.transactions import count_transactions, list_transactions
+from app.routers.transactions import count_transactions, list_transactions, normalize_sort
 from app.services.balances import account_balance, total_balance
 from app.services.planning_chart import refresh_planning_chart
 from app.services.projection_service import refresh_stale_projections
@@ -168,6 +168,8 @@ def buchungen(
     q: str | None = None,
     status: str = "confirmed",
     page: int = 1,
+    sort: str = "datum",
+    dir: str = "asc",
     session: Session = Depends(get_session),
 ):
     # HTML-Filterformular sendet leere Strings fuer nicht ausgefuellte Felder -
@@ -179,6 +181,7 @@ def buchungen(
     date_to = _opt_date(date_to)
     category_id = _opt_int(category_id)
     page = max(1, page)
+    sort, dir = normalize_sort(sort, dir)
     total = count_transactions(
         account_id=account_id,
         date_from=date_from,
@@ -197,6 +200,8 @@ def buchungen(
         category_id=category_id,
         q=q,
         status=status,
+        sort=sort,
+        dir=dir,
         limit=PAGE_SIZE,
         offset=(page - 1) * PAGE_SIZE,
         session=session,
@@ -217,6 +222,8 @@ def buchungen(
         },
         "page": page,
         "total_pages": total_pages,
+        "sort": sort,
+        "dir": dir,
     })