feat: add user search/filter, banned metric, mobile review API, event detail improvements

- admin_api/views.py: Add banned count to UserMetrics, fix server-side search/filter in UserListView
- admin_api/models.py: Add ReviewInteraction model, display_name/is_verified/helpful_count/flag_count to Review
- mobile_api/views/reviews.py: Customer-facing review submit/list/helpful/flag endpoints
- mobile_api/urls.py: Wire review API routes
- mobile_api/views/events.py: Event detail and listing improvements
- Security hardening across API modules

admin_api/models.py

@@ -34,6 +34,10 @@ class Review(models.Model):
     reject_reason   = models.CharField(
         max_length=15, choices=REJECT_CHOICES, null=True, blank=True
     )
+    display_name    = models.CharField(max_length=100, blank=True, default='')
+    is_verified     = models.BooleanField(default=False)
+    helpful_count   = models.IntegerField(default=0)
+    flag_count      = models.IntegerField(default=0)
 
     class Meta:
         ordering = ['-submission_date']
@@ -44,3 +48,18 @@ class Review(models.Model):
 
     def __str__(self):
         return f'Review #{self.pk} by {self.reviewer_id} — {self.status}'
+
+
+class ReviewInteraction(models.Model):
+    INTERACTION_CHOICES = [('HELPFUL', 'Helpful'), ('FLAG', 'Flag')]
+
+    review           = models.ForeignKey(Review, on_delete=models.CASCADE, related_name='interactions')
+    username         = models.CharField(max_length=255)
+    interaction_type = models.CharField(max_length=20, choices=INTERACTION_CHOICES)
+    created_at       = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        unique_together = ('review', 'username', 'interaction_type')
+
+    def __str__(self):
+        return f'{self.username} {self.interaction_type} on Review #{self.review_id}'