Post-merge cleanup previously continued past ownership-blocked remote
deletes, which skipped independently safe local worktree removal when the
only block was worktree_binding. Remove the clean owned worktree first,
reassess ownership, then delete the remote branch only if still safe.
Preserve fail-closed protection for dirty/foreign ownership categories.
Closes#851
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>