feat(2meet-data-optimizer): sample drift daily and record the result

- TMDO_Drift_Check::cron_tick() runs on the existing wpdo_daily_health_check event (no new schedule to add or clear): every entity type whose flat tables are written (dual_write or higher) is checked on 500 random entities per group, and the outcome replaces the recorded status, so a group found drifting leaves the router that day.
- Verify: DriftCheckTest cron cases (RED: method / hook missing); dev36 with all four entities in dual_write: one tick over 22 groups in 10 s, 0 drift, status option restored.
- PR: PR-073

includes/diagnostic/class-tmdo-drift-check.php

@@ -40,6 +40,11 @@ final class TMDO_Drift_Check {
 	 */
 	public const OPTION = 'wpdo_drift_status';
 
+	/**
+	 * Entities per group sampled by the daily check.
+	 */
+	public const CRON_SAMPLE = 500;
+
 	/**
 	 * MySQL regex for a plain decimal number, used to skip rows that obviously match.
 	 * Exact matches compare BINARY: meta and flat tables may differ in collation,
@@ -97,6 +102,24 @@ final class TMDO_Drift_Check {
 		return $report;
 	}
 
+	/**
+	 * Daily check (wpdo_daily_health_check): sample every entity type whose
+	 * flat tables are written (mode dual_write or higher). The outcome replaces
+	 * the recorded status, so a group found drifting leaves the router at once.
+	 */
+	public static function cron_tick(): void {
+		foreach ( TMDO_Entity_Registry::VALID_ENTITY_TYPES as $entity_type ) {
+			if ( ! TMDO_Mode_Manager::writes_to_flat( $entity_type ) ) {
+				continue;
+			}
+			try {
+				self::run( $entity_type, '', self::CRON_SAMPLE );
+			} catch ( InvalidArgumentException $e ) {
+				continue; // No adapter for this entity type on this site.
+			}
+		}
+	}
+
 	/**
 	 * Rebuild drifted flat rows from native meta, then check again.
 	 *