A project's `share` (absolute or a percentage of its parent's) is carved
from the parent; siblings never add up to more than the parent. v1 is
strict: a project holds at most its share. A project's own jobs and its
children without a share draw from its unassigned part. Borrowing idle
shares above a project's own (`max`) and reclaim are future work, in the
renamed project-borrowing brief.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
