Streamline first-run onboarding

[hamzamerzic]

Summary

• open new Möbius instances directly in the working shell instead of requiring an agent connection
• replace the blocking walkthrough with dismissible Settings and App Store guidance
• make Codex setup a clear device-access then connection flow with an official Data Controls link
• keep self-hosted first boot focused on username, password, and password confirmation

Verification

• npm test -- --runInBand (1,823 frontend tests + 47 hook tests)
• npm run build
• targeted ProviderAuth tests (6)