add manual validation request on the submission form

opus_submitter/submissions/models.py

@@ -242,6 +242,12 @@ class Submission(models.Model):
     validated_at = models.DateTimeField(
         null=True, blank=True, help_text="When this submission was validated"
     )
+    
+    # Manual validation request
+    manual_validation_requested = models.BooleanField(
+        default=False, 
+        help_text="Whether the user specifically requested manual validation"
+    )
 
     # Timestamps
     created_at = models.DateTimeField(auto_now_add=True)