feat: Hilfe-Seite mit Gebrauchsanleitung

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

finance/app/routers/gui.py

@@ -159,6 +159,11 @@ def _scenario_rows(session: Session, scenarios: list, loans: list) -> list[dict]
     return rows
 
 
+@router.get("/hilfe", dependencies=[Depends(gui_session)])
+def hilfe_page(request: Request):
+    return templates.TemplateResponse(request, "hilfe.html", {})
+
+
 @router.get("/planung", dependencies=[Depends(gui_session)])
 def planung_page(request: Request, session: Session = Depends(get_session)):
     categories = session.execute(select(Category)).scalars().all()