Feat: issue credit note on credit invoice - db change (#2676)

## Context

Now we don't allow creation of credit notes on prepaid credits. We want
to implement this possibility.
When credits will be issued, we'll be creating a voiding outbound
wallet_transaction. Currently we're tracking the outbound wallet
transactions. To support this behaviour we'll need to add credit_note_id
to the wallet transaction

## Description

Added credit_note_id to wallet_transaction

app/models/wallet_transaction.rb

@@ -4,7 +4,10 @@ class WalletTransaction < ApplicationRecord
   include PaperTrailTraceable
 
   belongs_to :wallet
+
+  # these two relationships are populated only for outbound transactions
   belongs_to :invoice, optional: true
+  belongs_to :credit_note, optional: true
 
   STATUSES = [
     :pending,
@@ -53,16 +56,19 @@ class WalletTransaction < ApplicationRecord
 #  transaction_type                    :integer          not null
 #  created_at                          :datetime         not null
 #  updated_at                          :datetime         not null
+#  credit_note_id                      :uuid
 #  invoice_id                          :uuid
 #  wallet_id                           :uuid             not null
 #
 # Indexes
 #
-#  index_wallet_transactions_on_invoice_id  (invoice_id)
-#  index_wallet_transactions_on_wallet_id   (wallet_id)
+#  index_wallet_transactions_on_credit_note_id  (credit_note_id)
+#  index_wallet_transactions_on_invoice_id      (invoice_id)
+#  index_wallet_transactions_on_wallet_id       (wallet_id)
 #
 # Foreign Keys
 #
+#  fk_rails_...  (credit_note_id => credit_notes.id)
 #  fk_rails_...  (invoice_id => invoices.id)
 #  fk_rails_...  (wallet_id => wallets.id)
 #

db/migrate/20241010055733_add_reference_to_credit_note_from_wallet_transaction.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AddReferenceToCreditNoteFromWalletTransaction < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def change
+    add_reference :wallet_transactions, :credit_note, type: :uuid, null: true, index: {algorithm: :concurrently}
+  end
+end

db/migrate/20241011123148_add_foreign_key_constraint_to_credit_note_id_at_wallet_transaction.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddForeignKeyConstraintToCreditNoteIdAtWalletTransaction < ActiveRecord::Migration[7.1]
+  def change
+    add_foreign_key :wallet_transactions, :credit_notes, validate: false
+  end
+end

db/migrate/20241011123621_change_validate_on_foreign_key_from_wallet_transaction_to_credit_note.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class ChangeValidateOnForeignKeyFromWalletTransactionToCreditNote < ActiveRecord::Migration[7.1]
+  def change
+    validate_foreign_key :wallet_transactions, :credit_notes
+  end
+end