test: validate the complete operator walkthrough

[fabiorosa]

Closes #27

What changed

• adds one explicit end-to-end operator walkthrough across desktop, keyboard, privacy, and 390 px states
• drives a deterministic failed event through real PostgreSQL, Redis, BullMQ, worker, Fastify destination, and Chromium
• verifies safe manual recovery, copied diagnostics, redacted UI output, and no horizontal overflow
• records the final browser-validation boundary and local Windows teardown limitation

Validation

• targeted Chromium walkthrough passed against real local processes
• formatting, lint, and strict typecheck pass
• the full local suite is subject to the documented Windows Playwright teardown and Docker Desktop availability limitation
• GitHub Actions Quality is the terminal full-suite gate