Adds a catalog picker to the member-booking form in the cashbox (prefills
amount/note/type, stays editable) and a "Buchen" button on each penalty
catalog entry that jumps to the cashbox with that entry preselected via a
penaltyId query param. No backend changes — reuses the existing POST
/transactions flow, the catalog only supplies starting values.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
