feat: enhance Immich integration with local copy option and validation for image handling

backend/server/integrations/models.py

@@ -9,6 +9,7 @@ class ImmichIntegration(models.Model):
     api_key = models.CharField(max_length=255)
     user = models.ForeignKey(
         User, on_delete=models.CASCADE)
+    copy_locally = models.BooleanField(default=True, help_text="Copy image to local storage, instead of just linking to the remote URL.")
     id = models.UUIDField(default=uuid.uuid4, editable=False, unique=True, primary_key=True)
 
     def __str__(self):