Re-home a session whose home worktree was removed

A session that followed its agent into a worktree stayed homed there after the worktree was removed (disposable agent worktrees are often deleted once their work merges): the old home could not be resolved, so re-homing was skipped, every later commit in the main checkout failed to link it, and a shadow branch was stranded. A home that no longer exists now never pins a session; the next strong signal re-homes it, leaving any pending work recorded there as it was.