Add OIDC authentication support using hanzo.id as the identity
provider for Lux Explorer user accounts.
- Add 'oidc' auth provider type alongside existing auth0/dynamic
- AuthGuardOidc: redirect-based OIDC login flow with CSRF state
- pages/auth/callback: authorization code exchange, token storage
- useApiFetch: pass Bearer token for OIDC-authenticated API calls
- account feature config: support NEXT_PUBLIC_OIDC_SERVER_URL and
NEXT_PUBLIC_OIDC_CLIENT_ID environment variables
- .env.production: configure hanzo.id as default OIDC provider