fix(2meet-data-optimizer): forget post status columns of groups whose flat table is gone

- on_transition() skips a recorded group whose table no longer exists and
  removes it from tmdo_post_status_columns; every post status change used to
  UPDATE the missing table and print a database error (seen on dev36 after a
  throwaway group's table was dropped)
- Verify: PostStatusSyncTest (dropped table), integration 578, unit 701, phpcs, stan
- PR: PR-106

includes/engine/class-tmdo-post-status-sync.php

@@ -65,6 +65,10 @@ final class TMDO_Post_Status_Sync {
 		unset( $new_status, $old_status );
 		foreach ( self::groups_with_columns() as $group ) {
 			$table = TMDO_Schema_Manager::get_table_name( 'post', $group );
+			if ( ! TMDO_Schema_Manager::table_exists( $table ) ) {
+				self::forget( $group ); // The table was dropped (retired or uninstalled group).
+				continue;
+			}
 			$wpdb->query(
 				$wpdb->prepare(
 					"UPDATE `{$table}` SET `post_status` = %s, `post_date` = %s WHERE `post_id` = %d", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
@@ -220,6 +224,20 @@ final class TMDO_Post_Status_Sync {
 		return is_array( $states ) ? array_keys( $states ) : array();
 	}
 
+	/**
+	 * Drop a group from the recorded states.
+	 *
+	 * @param string $group Group name.
+	 * @return void
+	 */
+	private static function forget( string $group ): void {
+		$states = get_option( self::OPTION, array() );
+		if ( is_array( $states ) && isset( $states[ $group ] ) ) {
+			unset( $states[ $group ] );
+			update_option( self::OPTION, $states, true );
+		}
+	}
+
 	/**
 	 * Record a group's state.
 	 *