Add OpenAPI fixture validation and fix fixtures to match API spec

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

tests/e2e/playwright.config.ts

@@ -8,6 +8,7 @@ import { defineConfig } from "@playwright/test";
 export default defineConfig({
   testDir: "./specs",
   timeout: 30000,
+  workers: 4,
   expect: { timeout: 5000 },
   use: {
     baseURL: "http://localhost:4173",