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/stores/pos.store.ts

@@ -16,12 +16,18 @@ interface POSState {
   cashier: POSUser | null
   token: string | null
   lastActivity: number
+  accountId: string | null
+  accountName: string | null
+  accountPhone: string | null
+  accountEmail: string | null
   setTransaction: (id: string | null) => void
   setLocation: (id: string) => void
   setDrawerSession: (id: string | null) => void
   unlock: (user: POSUser, token: string) => void
   lock: () => void
   touchActivity: () => void
+  setAccount: (id: string, name: string, phone?: string | null, email?: string | null) => void
+  clearAccount: () => void
   reset: () => void
 }
 
@@ -33,11 +39,17 @@ export const usePOSStore = create<POSState>((set) => ({
   cashier: null,
   token: null,
   lastActivity: Date.now(),
+  accountId: null,
+  accountName: null,
+  accountPhone: null,
+  accountEmail: null,
   setTransaction: (id) => set({ currentTransactionId: id }),
   setLocation: (id) => set({ locationId: id }),
   setDrawerSession: (id) => set({ drawerSessionId: id }),
   unlock: (user, token) => set({ locked: false, cashier: user, token, lastActivity: Date.now() }),
   lock: () => set({ locked: true, currentTransactionId: null }),
   touchActivity: () => set({ lastActivity: Date.now() }),
-  reset: () => set({ currentTransactionId: null }),
+  setAccount: (id, name, phone, email) => set({ accountId: id, accountName: name, accountPhone: phone ?? null, accountEmail: email ?? null }),
+  clearAccount: () => set({ accountId: null, accountName: null, accountPhone: null, accountEmail: null }),
+  reset: () => set({ currentTransactionId: null, accountId: null, accountName: null, accountPhone: null, accountEmail: null }),
 }))