Flow: Issue JWT → create data → list data

Demonstrates the authenticate-then-write pattern. Step 1 — POST /auth/token — issues a JWT for the demo user "alice". Step 2 — POST /api/v1/users — creates a user record in the session. Step 3 — GET /api/v1/users — lists the most recent 5 users in the session. Use the access_token from step 1 with the Authorization: Bearer header on real requests.