♻️(frontend) switch to Authorization Code flow

Instead of interacting with Keycloak, the frontend navigate to the
/authenticate endpoint, which starts the Authorization code flow.

When the flow is done, the backend redirect back to the SPA,
passing a session cookie and a csrf cookie.

Done:
- Query GET user/me to determine if user is authenticated yet
- Remove Keycloak js dependency, as all the OIDC logic is handled by the backend
- Store user's data instead of the JWT token

src/frontend/apps/e2e/playwright.config.ts

@@ -1,6 +1,6 @@
 import { defineConfig, devices } from '@playwright/test';
 
-const PORT = process.env.PORT || 3200;
+const PORT = process.env.PORT || 3000;
 
 const baseURL = `http://localhost:${PORT}`;