HR expense sequence

This module gives every expense report a unique reference number instead of leaving it blank. When a new expense report is created, Odoo automatically assigns the next number from a sequence called "Expense report sequence" (code hr.expense.sheet), which by default starts with the prefix EX followed by four digits, for example EX0001.

The number appears in several places: - On the expense report form, just before the employee field. - In the expense report list, before the report name. - In the search box: searching by text now also matches the reference number, not only the report name. - On the printed expense report, the number is displayed in the report header.

The reference is required and cannot be edited by users, and it is not copied when a report is duplicated, so each report keeps its own unique number. When the module is installed on an existing database, all previously created expense reports are automatically given a number in order of their creation.

The module works on the hr.expense.sheet model and depends on the standard Expenses application. It does not change how expenses are approved or paid; it only adds the reference numbering.