fix(2meet-data-optimizer): serve native meta in shadow_read and compare flat values

- In shadow_read, TMDO_Hook_Bus::intercept_get() returned the flat value.
  update_metadata() reads the old value through that filter after the Hook
  Bus has upserted the new one, so WP saw old === new and never wrote native
  meta: every update in shadow_read was lost on demotion (dev36 2026-09-26).
  shadow_read now returns $check (native) and compares flat on a sample of
  reads (filter tmdo_shadow_compare_sample_rate, default 0.1). aeav_only is
  unchanged; the post query router still routes in shadow_read.
- Live suite shadow_write: xfail markers removed, HivePress listing case
  added (new int key hp_rating_count); fixtures gain post() and a
  post_type-scoped field()/flat().
- Verify: live shadow_write + serialized 8/8 PASS (old code: 4 FAIL);
  unit 685 OK, integration 484 OK, phpcs (phpcs.xml) 0, stan OK
- PR: PR-056

tests/integration/HookBusIntegrationTest.php

@@ -268,6 +268,30 @@ class HookBusIntegrationTest extends TestCase {
 		$this->assertNull( $result, 'dual_write does not read from flat — must return $check' );
 	}
 
+	/**
+	 * shadow_read serves native meta: update_metadata() reads the old value
+	 * through this filter, and serving the just-written flat value made WP
+	 * skip the native write (dev36, 2026-09-26). Flat is only compared.
+	 */
+	public function test_get_serves_native_in_shadow_read_mode_even_with_a_flat_value(): void {
+		global $wpdb;
+		$wpdb->insert( self::FLAT_TABLE, array( 'user_id' => 12, 'first_name' => 'Flat' ) );
+		self::set_user_mode( WPDO_Mode_Manager::MODE_SHADOW_READ );
+
+		foreach ( array( 0.0, 1.0 ) as $rate ) {
+			$GLOBALS['_wp_filter_callbacks']['tmdo_shadow_compare_sample_rate'] = array(
+				static function () use ( $rate ) {
+					return $rate;
+				},
+			);
+
+			$result = WPDO_Hook_Bus::intercept_get( null, 12, 'first_name', true, 'user' );
+
+			$this->assertNull( $result, "shadow_read must return \$check (sample rate {$rate})" );
+		}
+		unset( $GLOBALS['_wp_filter_callbacks']['tmdo_shadow_compare_sample_rate'] );
+	}
+
 	public function test_get_returns_empty_string_when_column_is_null(): void {
 		global $wpdb;
 		$wpdb->query(