feat: add account linking and improve sales table

- Add many-to-many relationships between Sale/Expense and Account models
- Create pivot tables for account_sale and account_expense with migrations
- Implement account syncing during sale/expense creation and editing
- Add accounts_list attribute to display comma-separated account names
- Introduce SaleService with DTO for sale creation logic
- Simplify sales table columns to show branch, reference, date, and creator
- Calculate and store aggregated financial fields from transactions
- Make series field read-only instead of disabled in sale form

app/Filament/Resources/ExpenseResource.php

@@ -273,6 +273,7 @@ class ExpenseResource extends Resource
             Tables\Columns\TextColumn::make('branch.client.company'),
             Tables\Columns\TextColumn::make('branch.code'),
             Tables\Columns\TextColumn::make('happened_on'),
+            Tables\Columns\TextColumn::make('accounts_list')->label('Accounts'),
         ];
     }