History rewrite across many git worktrees: stash, map, verify the pop

When rewriting a clone's history after a scrubbed force-push, back up each dirty worktree's diff to a patch file and stash it with a message naming the worktree. All worktrees share one stash list, so pop each worktree's stash by looking up its index from the message, not by position. Indices shift after every pop, so redo the lookup each time. After popping, compare git diff against the saved patch to prove nothing was lost. Publish the old-to-new commit map to every agent or teammate before unfreezing, so reviews and handoffs that cite old SHAs can be translated. Also expect stale local branch refs that were behind origin before the rewrite to still be behind after it; that's normal, not a rewrite error.