payemnt billing and credits refactoring

backend/igny8_core/business/billing/models.py

@@ -336,6 +336,13 @@ class Invoice(AccountBaseModel):
     Invoice for subscription or credit purchases
     Tracks billing invoices with line items and payment status
     """
+    INVOICE_TYPE_CHOICES = [
+        ('subscription', 'Subscription'),
+        ('credit_package', 'Credit Package'),
+        ('addon', 'Add-on'),
+        ('custom', 'Custom'),
+    ]
+
     STATUS_CHOICES = [
         ('draft', 'Draft'),
         ('pending', 'Pending'),
@@ -345,6 +352,14 @@ class Invoice(AccountBaseModel):
     ]
     
     invoice_number = models.CharField(max_length=50, unique=True, db_index=True)
+
+    # Type
+    invoice_type = models.CharField(
+        max_length=30,
+        choices=INVOICE_TYPE_CHOICES,
+        default='custom',
+        db_index=True
+    )
     
     # Subscription relationship
     subscription = models.ForeignKey(
@@ -369,6 +384,10 @@ class Invoice(AccountBaseModel):
     invoice_date = models.DateField(db_index=True)
     due_date = models.DateField()
     paid_at = models.DateTimeField(null=True, blank=True)
+    expires_at = models.DateTimeField(null=True, blank=True)
+
+    # Void metadata
+    void_reason = models.TextField(blank=True)
     
     # Line items
     line_items = models.JSONField(default=list, help_text="Invoice line items: [{description, amount, quantity}]")