Fix invoice deletion integration tests and update documentation

Integration test fixes:
- Replace hardcoded status strings with proper CryptoPayment constants
- Fixed test_complete_refund_states_delete_invoice to use:
  - STATUS_LATEPAY_REFUNDED_COMPLETE
  - STATUS_UNDERPAID_REFUNDED_COMPLETE
  - STATUS_OUT_OF_STOCK_REFUNDED_COMPLETE
- Fixed test_no_refund_payment_deletes_invoice to use STATUS_LATEPAY_NOT_REFUNDED
- Updated all other status references to use constants instead of strings

The integration tests were failing because they used hardcoded strings like
"expired-refunded-complete" instead of the actual status constants from the model.
This caused the should_keep_invoice() logic to not work properly since the
status matching failed.

Documentation updates:
- Corrected "received" state description: detected in mempool (not blockchain)
- Added clarification about confirmations tracking via current_confirmations field
- Updated mempool detection rule explanation

All 11 invoice deletion integration tests now pass, confirming the invoice
deletion logic works correctly with real database operations.

make_post_sell/tests/test_invoice_deletion_integration.py

@@ -110,7 +110,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_expired_payment_deletes_invoice(self):
         """Test that expired payments have their invoices deleted."""
-        payment, invoice = self.create_crypto_payment_with_invoice("expired")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_EXPIRED)
 
         invoice_id = invoice.id
         payment_id = payment.id
@@ -139,7 +139,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_cancelled_payment_deletes_invoice(self):
         """Test that cancelled payments have their invoices deleted."""
-        payment, invoice = self.create_crypto_payment_with_invoice("cancelled")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_CANCELLED)
 
         invoice_id = invoice.id
 
@@ -153,7 +153,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_no_refund_payment_deletes_invoice(self):
         """Test that no-refund payments have their invoices deleted."""
-        payment, invoice = self.create_crypto_payment_with_invoice("no-refund")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_LATEPAY_NOT_REFUNDED)
 
         invoice_id = invoice.id
 
@@ -168,9 +168,9 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
     def test_complete_refund_states_delete_invoice(self):
         """Test that all complete refund states delete invoices."""
         complete_refund_states = [
-            "expired-refunded-complete",
-            "underpaid-refunded-complete",
-            "out-of-stock-refunded-complete",
+            CryptoPayment.STATUS_LATEPAY_REFUNDED_COMPLETE,
+            CryptoPayment.STATUS_UNDERPAID_REFUNDED_COMPLETE,
+            CryptoPayment.STATUS_OUT_OF_STOCK_REFUNDED_COMPLETE,
         ]
 
         for status in complete_refund_states:
@@ -189,7 +189,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_confirmed_payment_keeps_invoice(self):
         """Test that confirmed payments keep their invoices."""
-        payment, invoice = self.create_crypto_payment_with_invoice("confirmed")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_CONFIRMED)
 
         invoice_id = invoice.id
         payment_id = payment.id
@@ -211,7 +211,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_confirmed_overpaid_payment_keeps_invoice(self):
         """Test that confirmed-overpaid payments keep their invoices."""
-        payment, invoice = self.create_crypto_payment_with_invoice("confirmed-overpaid")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_CONFIRMED_OVERPAY)
 
         invoice_id = invoice.id
 
@@ -226,7 +226,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
     def test_confirmed_overpaid_refunded_payment_keeps_invoice(self):
         """Test that confirmed-overpaid-refunded payments keep their invoices."""
         payment, invoice = self.create_crypto_payment_with_invoice(
-            "confirmed-overpaid-refunded"
+            CryptoPayment.STATUS_CONFIRMED_OVERPAY_REFUNDED
         )
 
         invoice_id = invoice.id
@@ -272,7 +272,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
             quote_expires_at_ms=int((time.time() + 900) * 1000),
             confirmations_required=10,
         )
-        payment.status = "expired"
+        payment.status = CryptoPayment.STATUS_EXPIRED
         self.dbsession.add(payment)
         self.dbsession.flush()
 
@@ -296,7 +296,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
 
     def test_state_transition_triggers_invoice_deletion(self):
         """Test that changing payment state to terminal triggers invoice deletion."""
-        payment, invoice = self.create_crypto_payment_with_invoice("pending")
+        payment, invoice = self.create_crypto_payment_with_invoice(CryptoPayment.STATUS_PENDING)
 
         invoice_id = invoice.id
 
@@ -361,7 +361,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
             quote_expires_at_ms=int((time.time() + 900) * 1000),
             confirmations_required=10,
         )
-        payment1.status = "cancelled"
+        payment1.status = CryptoPayment.STATUS_CANCELLED
 
         payment2 = CryptoPayment(
             invoice=invoice,
@@ -376,7 +376,7 @@ class InvoiceDeletionIntegrationTests(DatabaseIntegrationTests):
             quote_expires_at_ms=int((time.time() + 900) * 1000),
             confirmations_required=10,
         )
-        payment2.status = "pending"
+        payment2.status = CryptoPayment.STATUS_PENDING
 
         self.dbsession.add(payment1)
         self.dbsession.add(payment2)