Add wallet balance to User model and implement Atoll/Island management

- Added `wallet_balance` field to the User model.
- Updated UserAdmin to include `wallet_balance` in the admin interface.
- Created serializers and views for Atoll and Island management.
- Implemented endpoints for listing, creating, and updating Atolls and Islands.
- Enhanced payment processing with UUIDs for Payment and Topup models.
- Added migration files for new fields and constraints.
- Improved error handling and validation in various views.
- Updated email templates for better responsiveness and SEO.

api/models.py

@@ -7,6 +7,7 @@ from django.db import models
 from .managers import CustomUserManager
 from django.utils import timezone
 
+
 class User(AbstractUser):
     email = models.EmailField(unique=True, blank=True, null=True)
     address = models.CharField(max_length=255, blank=True)
@@ -20,8 +21,13 @@ class User(AbstractUser):
     policy_accepted = models.BooleanField(default=False)
     wallet_balance = models.FloatField(default=0.0)
     ninja_user_id = models.CharField(max_length=255, blank=True)
-    atoll = models.ForeignKey('Atoll', on_delete=models.SET_NULL, null=True, blank=True, related_name='users')
-    island = models.ForeignKey('Island', on_delete=models.SET_NULL, null=True, blank=True, related_name='users')
+    atoll = models.ForeignKey(
+        "Atoll", on_delete=models.SET_NULL, null=True, blank=True, related_name="users"
+    )
+    island = models.ForeignKey(
+        "Island", on_delete=models.SET_NULL, null=True, blank=True, related_name="users"
+    )
+
     def get_all_fields(self, instance):
         return [field.name for field in instance.get_fields()]
 
@@ -29,16 +35,17 @@ class User(AbstractUser):
 
 
 class Atoll(models.Model):
-    name = models.CharField(max_length=255)
+    name = models.CharField(max_length=255, unique=True)
     created_at = models.DateTimeField(default=timezone.now)
     updated_at = models.DateTimeField(auto_now=True)
 
     def __str__(self):
         return self.name
 
+
 class Island(models.Model):
-    atoll = models.ForeignKey(Atoll, on_delete=models.CASCADE, related_name='islands')
-    name = models.CharField(max_length=255)
+    atoll = models.ForeignKey(Atoll, on_delete=models.CASCADE, related_name="islands")
+    name = models.CharField(max_length=255, unique=True)
     created_at = models.DateTimeField(default=timezone.now)
     updated_at = models.DateTimeField(auto_now=True)