Normalize supervisor emails and add unique constraint for case-insensitive email uniqueness

generic/models.py

@@ -5,6 +5,8 @@ import os
 from typing import Optional, Self, Tuple
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.db import models
+from django.db.models import UniqueConstraint
+from django.db.models.functions import Lower
 from django.forms import ValidationError
 from django.http import Http404, HttpRequest
 from django.shortcuts import render
@@ -1859,8 +1861,16 @@ class Supervisor(models.Model):
         return reverse("generic:supervisor_detail", kwargs={"pk": self.pk})
 
     def clean(self):
-        self.email = self.email.strip()
-        self.name = self.name.strip()
+        if self.email:
+            # normalize email: strip and lowercase for consistency
+            self.email = self.email.strip().lower()
+        if self.name:
+            self.name = self.name.strip()
+
+    class Meta:
+        constraints = [
+            UniqueConstraint(Lower('email'), name='unique_supervisor_email_ci')
+        ]
 
 
 @receiver(post_save, sender=User)