feat(perms): drop dead document export permissions; seed the 12 survivors via migration

offers.export/orders.export/invoices.export gated nothing on the backend (PDF
routes enforce *.view); they only toggled frontend buttons and showed dead
role checkboxes. Migration deletes them (+ role grants) and idempotently seeds
the 12 enforced doc perms (offers/orders/invoices x view/create/edit/delete) +
admin grant, so a fresh prod DB has them (closes the seed-only drift gap).
Route reverts to orders.view; the 8 frontend *.export checks now use *.view.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/IssuedOrderDetail.tsx

@@ -649,7 +649,7 @@ export default function IssuedOrderDetail() {
 
   // Form is editable only in create mode or while draft/sent.
   const editable = !isEdit || form.status === "draft" || form.status === "sent";
-  const canExport = hasPermission("orders.export");
+  const canExport = hasPermission("orders.view");
 
   // ─── Totals (live) ───
   const totals = useMemo(() => {