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/__tests__/issued-orders.test.ts

@@ -450,9 +450,20 @@ describe("GET /api/admin/issued-orders/suppliers", () => {
     const row = body.data.find((s: { id: number }) => s.id === active.id);
     expect(row.name).toBe("io_test_Aktivní dodavatel");
     expect(row.ico).toBe("12345678");
-    // Lightweight lookup shape — all picker fields present.
+    // Lightweight lookup shape — all picker fields present (structured
+    // address since the 2026-06 supplier customers-model split; the
+    // email/phone columns were dropped in favour of custom_fields).
     expect(Object.keys(row).sort()).toEqual(
-      ["address", "dic", "email", "ico", "id", "name", "phone"].sort(),
+      [
+        "city",
+        "country",
+        "dic",
+        "ico",
+        "id",
+        "name",
+        "postal_code",
+        "street",
+      ].sort(),
     );
   });
 
@@ -656,12 +667,15 @@ describe("renderIssuedOrderHtml", () => {
 
   const issuer = { name: "Jan Novák" };
 
-  // sklad_suppliers shape: single Text address blob + ico/dic columns.
+  // sklad_suppliers shape: structured address + ico/dic columns.
   const supplier = {
     name: "Dodavatel s.r.o.",
     ico: "12345678",
     dic: "CZ12345678",
-    address: "Průmyslová 5\n190 00 Praha",
+    street: "Průmyslová 5",
+    city: "Praha",
+    postal_code: "190 00",
+    country: "Česká republika",
   };
 
   it("renders the PO number, items, and both party names (PO direction)", () => {
@@ -685,7 +699,7 @@ describe("renderIssuedOrderHtml", () => {
     expect(html).toContain("Odběratel");
   });
 
-  it("renders the supplier address (split on newlines) plus IČO and DIČ", () => {
+  it("renders the structured supplier address plus IČO and DIČ", () => {
     const html = renderIssuedOrderHtml(
       order,
       items,
@@ -694,25 +708,26 @@ describe("renderIssuedOrderHtml", () => {
       "cs",
       issuer,
     );
-    // The single Text address blob becomes one address line per newline.
+    // street / "PSČ Město" / country — one address line each.
     expect(html).toContain('<div class="address-line">Průmyslová 5</div>');
     expect(html).toContain('<div class="address-line">190 00 Praha</div>');
+    expect(html).toContain('<div class="address-line">Česká republika</div>');
     expect(html).toContain("IČ: 12345678");
     expect(html).toContain("DIČ: CZ12345678");
   });
 
-  it("renders a no-newline address as a single line and skips missing IČO/DIČ", () => {
+  it("skips empty address parts and missing IČO/DIČ", () => {
     const html = renderIssuedOrderHtml(
       order,
       items,
-      { name: "Jednořádkový", address: "Ulice 1, 100 00 Praha" },
+      { name: "Jednořádkový", street: "Ulice 1", city: "Praha" },
       null,
       "cs",
       issuer,
     );
-    expect(html).toContain(
-      '<div class="address-line">Ulice 1, 100 00 Praha</div>',
-    );
+    expect(html).toContain('<div class="address-line">Ulice 1</div>');
+    // City without PSČ renders alone, no stray separator.
+    expect(html).toContain('<div class="address-line">Praha</div>');
     expect(html).not.toContain("IČ: ");
     expect(html).not.toContain("DIČ: ");
   });