Migration 0015 adds Project FK (SET_NULL, nullable) to Absence.
When is_paid=True, the auto-Bonus PayrollAdjustment inherits the
project for cost-attribution. Form + admin + list + edit + log
templates expose the field. List view filter now uses
absence.project_id directly (was indirect via worker__work_logs).
5 new tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>