feat(web): highlight the offending field on a set_fields 422 (#28)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/objects/object-edit-form.test.tsx

@@ -17,6 +17,26 @@ function tree() {
   );
 }
 
+test("edit: fields PUT 422 with field body -> field error message shown and field marked invalid", async () => {
+  server.use(
+    http.get("/api/admin/objects/:id", () =>
+      HttpResponse.json({ ...amphora, fields: { inscription: "old" } }),
+    ),
+    http.put("/api/admin/objects/:id", () => new HttpResponse(null, { status: 204 })),
+    http.put("/api/admin/objects/:id/fields", () =>
+      HttpResponse.json({ field: "inscription", code: "type_mismatch" }, { status: 422 }),
+    ),
+  );
+
+  renderApp(tree(), { route: `/objects/${amphora.id}/edit` });
+
+  await screen.findByDisplayValue("Amphora");
+  await userEvent.click(screen.getByRole("button", { name: /save/i }));
+
+  const alerts = await screen.findAllByText(/inscription.*rejected/i);
+  expect(alerts.length).toBeGreaterThanOrEqual(2);
+});
+
 test("edit: prefilled, save -> PUT core + PUT fields -> back to detail", async () => {
   let putCore: unknown;
   let putFields: unknown;