Ln 302 Task Replanner

This handles the messy job of syncing your Linear tasks back to reality when requirements shift mid-sprint. It loads existing tasks, compares them against an ideal plan, then classifies each as KEEP, UPDATE, OBSOLETE, or CREATE before applying the changes. The smart bit is the no-op fast path: if nothing actually needs updating after normalization, it skips all mutations and just returns a clean summary. It runs standalone or under a coordinator, writes machine-readable summaries, and blocks any task creation that's missing the seven mandatory body sections. Use it when your Story definition changed and you need to reconcile without manual ticket archaeology.