feat(share-products): retire the Share Reference mapping, remove dead Cashier Share Collection screen

Share Products:
- "Share Reference (Cash Vault or Suspense)" removed from the accounting step (create, edit,
  preview and the read-only view tab) -- every register now books a share transaction against the
  account the money actually reached, so no product needs a placeholder asset mapping any more.
  The field is now optional server-side, not required.

Cashier:
- Removed the Share Collection screen and its three service methods. It read
  m_share_account.cashier_collected, a column that has never existed in this schema, and no other
  screen ever called it -- it could not have produced a working entry.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/app/cashier/cashier.module.ts

@@ -20,7 +20,6 @@ import { ReconciliationComponent } from './reconciliation/reconciliation.compone
 import { CashHistoryComponent } from './cash-history/cash-history.component';
 import { ClosingCashReportComponent } from './closing-cash-report/closing-cash-report.component';
 import { ExcessTransactionReportComponent } from './excess-transaction-report/excess-transaction-report.component';
-import { ShareCollectionComponent } from './share-collection/share-collection.component';
 
 @NgModule({
   imports: [
@@ -35,8 +34,7 @@ import { ShareCollectionComponent } from './share-collection/share-collection.co
     ReconciliationComponent,
     CashHistoryComponent,
     ClosingCashReportComponent,
-    ExcessTransactionReportComponent,
-    ShareCollectionComponent
+    ExcessTransactionReportComponent
   ]
 })
 export class CashierModule {}