feat: wire home, did_document, and recovery_info steps into OnboardingStep state machine
- Replace 'authenticated' step with 'home', 'did_document', 'recovery_info' steps
- Add homeData state to page level so sub-screens receive already-loaded data
- Create stub DIDDocumentScreen and RecoveryInfoScreen components (replaced by Phases 5-6)
- Wire HomeScreen callbacks to navigate to sub-screens and back
- Update auth_ready listener to navigate to 'home' instead of 'authenticated'
- Update AuthenticatingScreen callback to navigate to 'home'
- Clean up unused .oauth-body CSS from removed authenticated block
Verifies: MM-150.AC3.4, MM-150.AC3.9, MM-150.AC3.10, MM-150.AC3.14, MM-150.AC5.1, MM-150.AC5.2