Bump playkit to v0.3 and use Zod API schemas

Adopt assertSchema via ApiClient, playkitFailureArtifacts in Playwright
config, and keep e2e login on e2e@levkine.ca credentials from CI secrets.

e2e/playwright.config.ts

@@ -1,4 +1,5 @@
 import { defineConfig, devices } from '@playwright/test';
+import { playkitFailureArtifacts } from '@levkin/playkit';
 import { DEFAULT_BASE_URL } from './env-defaults';
 
 const baseURL =
@@ -17,9 +18,7 @@ export default defineConfig({
   expect: { timeout: 15_000 },
   use: {
     baseURL,
-    trace: 'retain-on-failure',
-    screenshot: 'only-on-failure',
-    video: 'retain-on-failure',
+    ...playkitFailureArtifacts(),
     ...devices['Desktop Chrome'],
   },
   projects: [{ name: 'chromium', use: { ...devices['Desktop Chrome'] } }],