feat: add POS register screen with full-screen touch-optimized layout

Standalone register at /pos bypassing the admin sidebar layout:
- Two-panel layout: product search/grid (60%) + cart/payment (40%)
- Product search with barcode scan support (UPC lookup on Enter)
- Custom item entry dialog for ad-hoc items
- Cart with line items, tax, totals, and remove-item support
- Payment dialogs: cash (quick amounts + change calc), card, check
- Drawer open/close with balance reconciliation and over/short
- Auto-creates pending transaction on first item added
- POS link added to admin sidebar nav (module-gated)
- Zustand store for POS session state, React Query for server data

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

packages/admin/src/routeTree.gen.ts

@@ -9,6 +9,7 @@
 // Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
 
 import { Route as rootRouteImport } from './routes/__root'
+import { Route as PosRouteImport } from './routes/pos'
 import { Route as LoginRouteImport } from './routes/login'
 import { Route as AuthenticatedRouteImport } from './routes/_authenticated'
 import { Route as AuthenticatedIndexRouteImport } from './routes/_authenticated/index'
@@ -56,6 +57,11 @@ import { Route as AuthenticatedAccountsAccountIdMembersRouteImport } from './rou
 import { Route as AuthenticatedAccountsAccountIdEnrollmentsRouteImport } from './routes/_authenticated/accounts/$accountId/enrollments'
 import { Route as AuthenticatedLessonsScheduleInstructorsInstructorIdRouteImport } from './routes/_authenticated/lessons/schedule/instructors/$instructorId'
 
+const PosRoute = PosRouteImport.update({
+  id: '/pos',
+  path: '/pos',
+  getParentRoute: () => rootRouteImport,
+} as any)
 const LoginRoute = LoginRouteImport.update({
   id: '/login',
   path: '/login',
@@ -323,6 +329,7 @@ const AuthenticatedLessonsScheduleInstructorsInstructorIdRoute =
 export interface FileRoutesByFullPath {
   '/': typeof AuthenticatedIndexRoute
   '/login': typeof LoginRoute
+  '/pos': typeof PosRoute
   '/help': typeof AuthenticatedHelpRoute
   '/profile': typeof AuthenticatedProfileRoute
   '/settings': typeof AuthenticatedSettingsRoute
@@ -369,6 +376,7 @@ export interface FileRoutesByFullPath {
 }
 export interface FileRoutesByTo {
   '/login': typeof LoginRoute
+  '/pos': typeof PosRoute
   '/help': typeof AuthenticatedHelpRoute
   '/profile': typeof AuthenticatedProfileRoute
   '/settings': typeof AuthenticatedSettingsRoute
@@ -417,6 +425,7 @@ export interface FileRoutesById {
   __root__: typeof rootRouteImport
   '/_authenticated': typeof AuthenticatedRouteWithChildren
   '/login': typeof LoginRoute
+  '/pos': typeof PosRoute
   '/_authenticated/help': typeof AuthenticatedHelpRoute
   '/_authenticated/profile': typeof AuthenticatedProfileRoute
   '/_authenticated/settings': typeof AuthenticatedSettingsRoute
@@ -467,6 +476,7 @@ export interface FileRouteTypes {
   fullPaths:
     | '/'
     | '/login'
+    | '/pos'
     | '/help'
     | '/profile'
     | '/settings'
@@ -513,6 +523,7 @@ export interface FileRouteTypes {
   fileRoutesByTo: FileRoutesByTo
   to:
     | '/login'
+    | '/pos'
     | '/help'
     | '/profile'
     | '/settings'
@@ -560,6 +571,7 @@ export interface FileRouteTypes {
     | '__root__'
     | '/_authenticated'
     | '/login'
+    | '/pos'
     | '/_authenticated/help'
     | '/_authenticated/profile'
     | '/_authenticated/settings'
@@ -609,10 +621,18 @@ export interface FileRouteTypes {
 export interface RootRouteChildren {
   AuthenticatedRoute: typeof AuthenticatedRouteWithChildren
   LoginRoute: typeof LoginRoute
+  PosRoute: typeof PosRoute
 }
 
 declare module '@tanstack/react-router' {
   interface FileRoutesByPath {
+    '/pos': {
+      id: '/pos'
+      path: '/pos'
+      fullPath: '/pos'
+      preLoaderRoute: typeof PosRouteImport
+      parentRoute: typeof rootRouteImport
+    }
     '/login': {
       id: '/login'
       path: '/login'
@@ -1069,6 +1089,7 @@ const AuthenticatedRouteWithChildren = AuthenticatedRoute._addFileChildren(
 const rootRouteChildren: RootRouteChildren = {
   AuthenticatedRoute: AuthenticatedRouteWithChildren,
   LoginRoute: LoginRoute,
+  PosRoute: PosRoute,
 }
 export const routeTree = rootRouteImport
   ._addFileChildren(rootRouteChildren)