feat(sales): add discount support with ledger accounting

- Add discount_type column to transactions table via migration
- Update Sale model to use fillable instead of guarded for better security
- Implement discount account ledger creation when discount is applied
- Fix net amount calculation to include discount in CreateSaleAction
- Remove unused "Exempt" column from sale transaction table
- Make discount_type required when discount is enabled in form
- Update form data mutation to properly handle discount calculations

app/Actions/Transactions/CreateTransactionAction.php

@@ -24,6 +24,10 @@ class CreateTransactionAction extends BaseAction
 
         $this->cashAccountLedger($payload);
 
+        if ($payload->transaction->discount !== 0) {
+            $this->discountAccountLedger($payload);
+        }
+
         return $next($payload);
     }
 
@@ -33,11 +37,13 @@ class CreateTransactionAction extends BaseAction
         $isExpense = $payload->transactionable instanceof \App\Models\Expense;
         $type = $isExpense ? 'debit' : 'credit';
 
+        $discount = $payload->transaction->discount ?? 0.00;
+
         if ($branch->isClientVatable) {
             //create transaction account ledger
             $ledgerPayload = new CreateLedgerDTO(
                 branch_id: $payload->transactionable->branch_id,
-                amount: $payload->transaction->net_amount ?? 0.00,
+                amount: $payload->transaction->net_amount + $discount ?? 0.00,
                 transaction: $payload->transaction,
                 account: $payload->transaction->account,
                 type: $type,
@@ -144,4 +150,28 @@ class CreateTransactionAction extends BaseAction
             $this->ledgerPipe($ledgerPayload);
         }
     }
+
+    public function discountAccountLedger($payload): void
+    {
+        $isExpense = $payload->transactionable instanceof \App\Models\Expense;
+        $type = $isExpense ? 'credit' : 'debit';
+        $amount = $payload->transaction->discount ?? 0.00;
+        $clientId = $payload->transactionable->branch->client_id;
+
+        $discountAccount = Account::query()
+            ->where('account', 'Sales Discount')
+            ->where('client_id', $clientId)
+            ->first();
+
+        if ($discountAccount && $amount > 0) {
+            $ledgerPayload = new CreateLedgerDTO(
+                branch_id: $payload->transactionable->branch_id,
+                amount: $amount,
+                transaction: $payload->transaction,
+                account: $discountAccount,
+                type: $type,
+            );
+            $this->ledgerPipe($ledgerPayload);
+        }
+    }
 }