feat: customer lookup from POS with order history and item search

- Customer dialog in cart panel: search accounts by name, phone, email, account #
- Selected customer shown with name, phone, email in cart header
- accountId passed when creating transactions
- Order history view: tap a transaction to expand and see line items
- Item search in history (e.g. "strings") — filters orders containing that item
- Backend: add accountId and itemSearch filters to transaction list endpoint
- itemSearch uses EXISTS subquery on line item descriptions (ILIKE)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/admin/src/components/pos/pos-item-panel.tsx

@@ -16,7 +16,7 @@ interface POSItemPanelProps {
 
 export function POSItemPanel({ transaction: _transaction }: POSItemPanelProps) {
   const queryClient = useQueryClient()
-  const { currentTransactionId, setTransaction, locationId } = usePOSStore()
+  const { currentTransactionId, setTransaction, locationId, accountId } = usePOSStore()
   const [search, setSearch] = useState('')
   const [customOpen, setCustomOpen] = useState(false)
   const [customDesc, setCustomDesc] = useState('')
@@ -40,6 +40,7 @@ export function POSItemPanel({ transaction: _transaction }: POSItemPanelProps) {
         const txn = await posMutations.createTransaction({
           transactionType: 'sale',
           locationId: locationId ?? undefined,
+          accountId: accountId ?? undefined,
         })
         txnId = txn.id
         setTransaction(txnId)
@@ -66,6 +67,7 @@ export function POSItemPanel({ transaction: _transaction }: POSItemPanelProps) {
         const txn = await posMutations.createTransaction({
           transactionType: 'sale',
           locationId: locationId ?? undefined,
+          accountId: accountId ?? undefined,
         })
         txnId = txn.id
         setTransaction(txnId)
@@ -96,6 +98,7 @@ export function POSItemPanel({ transaction: _transaction }: POSItemPanelProps) {
         const txn = await posMutations.createTransaction({
           transactionType: 'sale',
           locationId: locationId ?? undefined,
+          accountId: accountId ?? undefined,
         })
         txnId = txn.id
         setTransaction(txnId)