Fix employee workshop lookups using positional bindings

[Kettailor]

Motivation

• Fix a PDOException: SQLSTATE[HY093]: Invalid parameter number caused by reusing the same named parameter multiple times in workshop lookup queries.
• Prevent failures when resolving workshop access that surface in warehouse flows (stack trace referenced Employee::getWorkshopIdsForEmployee).
• Make employee-to-workshop membership checks more reliable across different PDO drivers.
• Reduce runtime errors when creating/updating warehouses that validate employee workshop membership.

Description

• Replaced repeated named placeholders with positional ? placeholders in models/Employee.php for getWorkshopIdsForEmployee.
• Applied the same positional binding fix to isEmployeeInWorkshop and bound the workshop id as the fourth parameter.
• Updated parameter binding calls to numeric indexes using bindValue(1, ...), bindValue(2, ...), etc.
• Change is limited to models/Employee.php to address the invalid-parameter error without altering query semantics.

Testing

• No automated tests were run on this change.

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Codex Task