Introduces a 5-step guided flow (Create Account → Add Wallet → Alert
Rules → Notifications → Done) that takes new users from zero to fully
configured alerts in one linear session. /signup now redirects to
/onboarding; already-onboarded users who revisit /onboarding are
redirected to /addresses.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
