feat(suppliers)!: full customers model - structured address + custom fields

The dodavatele modal is now an exact mirror of the customers modal
(minus the PDF field-order picker): Nazev+ARES, Ulice, Mesto+PSC, Zeme,
ICO+ARES, DIC, and the same "Vlastni pole" editor (maxWidth md).

Two migrations on sklad_suppliers:
- structured street/city/postal_code/country replace the free-text
  address blob (best-effort split: street / PSC regex / city)
- custom_fields LONGTEXT replaces contact_person/email/phone/notes;
  existing values are preserved as labeled custom fields

The encode/decode of the custom_fields blob is shared with customers
via the new utils/custom-fields.ts. The PO PDF supplier block renders
the structured address + custom-field lines like the customer block;
the supplier picker/detail selects and types follow. Legacy clients
sending the dropped keys are silently stripped (tested). Suppliers
list shows Ulice/Mesto instead of the dropped contact columns; search
covers name/ico/city.

BREAKING CHANGE: sklad_suppliers.address, contact_person, email,
phone, notes columns dropped (data migrated); deploy must run
prisma migrate deploy + generate.

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

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

@@ -25,9 +25,10 @@ export interface Supplier {
   name: string;
   ico: string | null;
   dic: string | null;
-  address: string | null;
-  email: string | null;
-  phone: string | null;
+  street: string | null;
+  city: string | null;
+  postal_code: string | null;
+  country: string | null;
 }
 
 export interface IssuedOrderItem {

src/admin/lib/queries/warehouse.ts

@@ -157,16 +157,23 @@ export interface WarehouseLocation {
   is_active: boolean;
 }
 
+export interface WarehouseSupplierCustomField {
+  name: string;
+  value: string;
+  showLabel: boolean;
+  _key?: string;
+}
+
 export interface WarehouseSupplier {
   id: number;
   name: string;
   ico: string | null;
   dic: string | null;
-  contact_person: string | null;
-  email: string | null;
-  phone: string | null;
-  address: string | null;
-  notes: string | null;
+  street: string | null;
+  city: string | null;
+  postal_code: string | null;
+  country: string | null;
+  custom_fields?: WarehouseSupplierCustomField[];
   is_active: boolean;
 }