feat(issued-orders): counterparty is now a supplier (dodavatel), not a customer

Issued orders are purchase orders WE send - they must pick from suppliers
(sklad_suppliers), not from customers. Per user decision customer_id was
REPLACED (not kept alongside): migration drops issued_orders.customer_id and
adds supplier_id FK -> sklad_suppliers (existing rows lose their counterparty
- the feature is days old; re-point them in the UI).

- service: input/filters/search (suppliers.name + ico)/enrichment/detail all
  supplier-based; create validates the supplier inside the transaction and
  update before write -> Czech 400 'Dodavatel nenalezen' instead of P2003 500;
  detail returns a minimal supplier field set (no internal notes leak)
- routes: supplier_id on list + stats; new GET /issued-orders/suppliers
  lookup (orders.view/create/edit guard - orders users lack warehouse.manage
  which guards the warehouse suppliers CRUD), active suppliers only,
  name+id ordering
- PDF: Dodavatel block now renders the supplier (name, newline-split address,
  IC/DIC), layout and both language label sets unchanged
- frontend: new SupplierPicker kit component (CustomerPicker untouched),
  IssuedOrderDetail/IssuedOrders switched to supplier_id/supplier_name; the
  picker keeps a fallback option for orders whose supplier was later
  deactivated; WarehouseSuppliers CRUD now also invalidates issued-orders so
  the picker can't go stale
- tests: issued-orders suite switched to supplier fixtures + new coverage
  (lookup shape + 403, nonexistent supplier 400, PDF supplier block)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/admin/lib/queries/issued-orders.ts

@@ -4,8 +4,8 @@ import { jsonQuery, paginatedJsonQuery } from "../apiAdapter";
 export interface IssuedOrder {
   id: number;
   po_number: string | null;
-  customer_id: number | null;
-  customer_name: string | null;
+  supplier_id: number | null;
+  supplier_name: string | null;
   status: string;
   currency: string | null;
   order_date: string | null;
@@ -14,6 +14,17 @@ export interface IssuedOrder {
   total: number;
 }
 
+/** Active supplier row from the lightweight PO-picker lookup endpoint. */
+export interface Supplier {
+  id: number;
+  name: string;
+  ico: string | null;
+  dic: string | null;
+  address: string | null;
+  email: string | null;
+  phone: string | null;
+}
+
 export interface IssuedOrderItem {
   id?: number;
   description: string | null;
@@ -37,10 +48,19 @@ export interface IssuedOrderDetail extends IssuedOrder {
   notes: string | null;
   internal_notes: string | null;
   items: IssuedOrderItem[];
-  customer: Record<string, unknown> | null;
+  supplier: Record<string, unknown> | null;
   valid_transitions: string[];
 }
 
+// Suppliers lookup for the PO supplier picker — hits the issued-orders-scoped
+// endpoint (orders permissions), NOT the warehouse.manage-guarded CRUD list.
+export const issuedOrderSuppliersOptions = () =>
+  queryOptions({
+    queryKey: ["issued-orders", "suppliers"],
+    queryFn: () => jsonQuery<Supplier[]>("/api/admin/issued-orders/suppliers"),
+    staleTime: 2 * 60_000,
+  });
+
 export const issuedOrderListOptions = (filters: {
   search?: string;
   sort?: string;