refactor(2meet-data-optimizer): stop registering the sso group in core

- TMDO_Member_Fields no longer registers user/sso; the definition moved
  unchanged (hash 03543f19) to 2meet-data-optimizer-sso-addon.
- missing_integration_addons(): 2meet-hub-core or 2meet-spoke-sso without
  the SSO AddOn is reported (admin notice + Site Health).
- The deprecated-AddOn notice points hub / spoke users to the SSO AddOn.
- Sites must activate the SSO AddOn before this ships (PR-041); aeav_only
  sites without it fall back to orphan-group restore.
- Verify: core unit 659 / integration 475, SSO 6, HP 142/49, WC 10/22
  green, phpcs clean
- PR: PR-040

tests/unit/MissingIntegrationAddonsTest.php

@@ -79,6 +79,27 @@ class MissingIntegrationAddonsTest extends TestCase {
 		$this->assertSame( array( 'WooCommerce' => '2meet-data-optimizer-woocommerce-addon' ), TMDO_Compatibility::missing_integration_addons() );
 	}
 
+	/**
+	 * @runInSeparateProcess
+	 * @preserveGlobalState disabled
+	 */
+	public function test_hub_or_spoke_without_the_sso_addon_is_reported(): void {
+		eval( 'final class TMSO_Plugin {}' );
+
+		$this->assertSame( array( '2meet Hub / Spoke SSO' => '2meet-data-optimizer-sso-addon' ), TMDO_Compatibility::missing_integration_addons() );
+	}
+
+	/**
+	 * @runInSeparateProcess
+	 * @preserveGlobalState disabled
+	 */
+	public function test_hub_with_the_sso_addon_is_fine(): void {
+		eval( 'final class TMHC_Plugin {}' );
+		eval( 'final class TMDO_SSO_Integration {}' );
+
+		$this->assertSame( array(), TMDO_Compatibility::missing_integration_addons() );
+	}
+
 	/**
 	 * @runInSeparateProcess
 	 * @preserveGlobalState disabled