Cashup: configurable card machines — settings + inline Z-report layout

Settings: add Card Machines section to configure number of PDQ terminals
and their names (1–6 machines, defaults to Front Desk + Restaurant / Bar).
Names are stored under the 'card_machines' settings key.

DailyCashUp: machine names now load from settings instead of hardcoded
const. Card Machines section changed from a 2-column grid to a vertical
list; each machine row shows the amount inputs on the left and its PDQ
Z-report photo uploader on the right. Separate PDQ Z-Reports card removed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/routes/settings.js

@@ -5,6 +5,7 @@ import { testConnection, fetchGlAccountsGrouped } from '../lib/newbook.js'
 const ALL_KEYS = [
   'default_report_days', 'petty_cash_float', 'till_float_target',
   'sales_breakdown_columns', 'change_tin_breakdown', 'change_tin_notes',
+  'card_machines',
 ]
 
 export async function settingsRoutes(app) {