Set up initial playwright testing fixes #296

[taramk]

• Add Playwright E2E test infrastructure with Chromium, virtual WebAuthn authenticator, and MailSlurp for email OTP — enabling automated testing of the full passkey-based signup flow
• Introduce a setup project that runs once before all tests, creates a real test account via Hanko auth, and saves the browser session to tests/.auth/user.json so subsequent tests start already logged in
• Add first authenticated test: verifies a signed-in user lands on the dashboard and sees the Projects heading
• Configure test retries, 30s action/navigation timeouts, and automatic wrangler dev server startup via webServer in playwright.config.ts
• Update .gitignore to exclude test auth state (tests/.auth/), local Claude settings
• Add MAILSLURP_API_KEY to .env.example to document the required secret for collaborators

[progrium]

Looks good, I think the only thing I'd suggest is putting package.json and the other files in the project root in tests because they are just for tests. But I'll merge this now to unblock.