feat(identity-wallet): add IdentityListHome component
- Creates new multi-identity home screen showing all claimed identities as cards
- Each card displays avatar, handle, truncated DID, and PDS endpoint
- Includes rotation key status badge (Root Key/Not Root/Unknown) in green/amber/gray
- Implements empty state when no identities exist with 'Add Identity' button
- Cards are tappable to navigate to identity detail view
- Includes refresh button to reload all identities
- Plus button navigates back to mode selector to add another identity
- Lazy-loads DID documents and device key IDs in parallel for each identity
- Reuses DIDAvatar component for deterministic avatar colors
- Follows HomeScreen styling patterns with card-based layout