hr_contract_employee_calendar_planning

Align contract resource calendars with employee calendar planning so working time history stays consistent when both modules are used.

Key Features

hr.employee: A post-init migration copies each contract's resource calendar into the employee's calendar_ids with matching dates to preserve historical work schedules.
hr.contract: Contract creation forces resource_calendar_id to match the employee's auto-generated calendar so new contracts cannot introduce divergent schedules.
hr.contract: Write operations ignore resource_calendar_id updates when they would overwrite the employee calendar, keeping planning data authoritative.
hr.contract.history: Form views hide resource_calendar_id fields to guide users to manage working times exclusively through employee calendar planning.