feat(favorites): add EventLike model, favorites API, and notifications module

- EventLike model (user × event unique constraint, indexed)
- contributed_by field on Event (EVT ID or email of community contributor)
- Favorites API endpoints: toggle-like, my-likes, my-liked-events
- Notifications app wired into main urls.py at /api/notifications/
- accounts migration 0014_merge_0013 (resolves split 0013 branches)
- requirements.txt updated

events/models.py

@@ -58,6 +58,11 @@ class Event(models.Model):
     is_featured = models.BooleanField(default=False, help_text='Show this event in the featured section')
     is_top_event = models.BooleanField(default=False, help_text='Show this event in the Top Events section')
 
+    contributed_by = models.CharField(
+        max_length=100, blank=True, null=True,
+        help_text='Eventify ID (EVT-XXXXXXXX) or email of the community contributor',
+    )
+
     def __str__(self):
         return f"{self.name} ({self.start_date})"
 
@@ -71,3 +76,26 @@ class EventImages(models.Model):
         return f"{self.event_image}"
 
 
+class EventLike(models.Model):
+    user = models.ForeignKey(
+        'accounts.User',
+        on_delete=models.CASCADE,
+        related_name='event_likes'
+    )
+    event = models.ForeignKey(
+        Event,
+        on_delete=models.CASCADE,
+        related_name='likes'
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        unique_together = ('user', 'event')
+        indexes = [
+            models.Index(fields=['user', '-created_at']),
+        ]
+
+    def __str__(self):
+        return f"{self.user.email} likes {self.event.name}"
+
+