fix(quick-002): prevent duplicate mentor notifications on job republish

- Add post meta guard `_ddhh_mentors_notified` to track notification status
- Check meta before scheduling notifications, skip if already notified
- Set meta flag after successful batch scheduling
- Prevents re-notification when job edited and republished (pending -> publish)
- Maintains existing publish -> publish guard logic

includes/class-notifications.php

@@ -438,6 +438,18 @@ class DDHH_JM_Notifications {
 			return;
 		}
 
+		// Check if mentors have already been notified for this job
+		$already_notified = get_post_meta( $post->ID, '_ddhh_mentors_notified', true );
+		if ( '1' === $already_notified ) {
+			error_log(
+				sprintf(
+					'DDHH Job Manager: Skipping mentor notification for job #%d - mentors already notified on initial publish',
+					$post->ID
+				)
+			);
+			return;
+		}
+
 		// Get opted-in mentors
 		$mentor_ids = DDHH_JM_User_Preferences::get_opted_in_mentors();
 
@@ -456,6 +468,9 @@ class DDHH_JM_Notifications {
 		// Schedule async batch notifications
 		$batch_count = DDHH_JM_Scheduler::schedule_mentor_notification_batch( $mentor_ids, $post->ID );
 
+		// Mark job as having notified mentors to prevent duplicate notifications
+		update_post_meta( $post->ID, '_ddhh_mentors_notified', '1' );
+
 		// Log success
 		error_log(
 			sprintf(