/claim #8042

Adds an OAuth Registration Allowed toggle in Settings > Advanced that allows new users to self-register via OAuth providers even when general registration is disabled.

Problem

Currently, OAuth users cannot register when is_registration_enabled is false. This prevents admins from using identity providers (Authentik, Keycloak, etc.) to control access while blocking manual registration.

Solution

• New is_oauth_registration_enabled boolean in instance_settings (default: false)
• OauthController now allows registration when either is_registration_enabled OR is_oauth_registration_enabled is true
• Toggle added to Settings > Advanced with clear helper text

Changes (4 files)

1. Migration - Adds is_oauth_registration_enabled column
2. OauthController - Checks both flags before blocking registration
3. Advanced.php (Livewire) - Wires the new setting
4. advanced.blade.php - Adds the checkbox UI

Behavior

Existing OAuth users can always log in regardless of these settings.

Fixes #8042