siblings.py (make siblings) and the doctor: a dangling symlink at ../<Project> reads as an empty slot, so the dry run says "would clone" and the doctor says absent, while the real run ends CLONE FAILED #784

Goal: a dangling symlink at a member's sibling slot is NOT A CLONE in make siblings, in its dry run and in the doctor's members row alike. It is a link to nothing, and cloning into it fails.

Filed by lane openRepoShape-3 under v1.1.1, on Brett Heap's word of 2026-10-16T13:35:28Z ("yes create v1.1.1"). Lane 3's reviewer RV-d measured it while reviewing #772 (#735), as N2 (#772 (comment)). Main behaves the same, so it is not a regression; it is not a traceback either, so it was outside #735.

What happens (on #772's head 1d149933 and on main), with a dangling symlink at ../IRRS in a two-member holder:

• make siblings dry run: "would clone" IRRS.
• The real make siblings: CLONE FAILED. git cannot clone into a path that is a link to nothing.
• The doctor's members row: calls the slot absent, with its "places them" note.
• make park and make resume: SKIPPED no clone (siblings.py: a file, or a folder make siblings cannot list or enter, at ../<Project> is NOT A CLONE, reported and left as it is, so the run no longer ends in a traceback at iterdir before the members after it are placed, and make park no longer ends in one over a folder it cannot enter (#735) #772).

Fix:

• siblings.py not_a_clone (templates/family-root/scripts/siblings.py:488 at 1d149933) should treat target.is_symlink() and not target.exists() as NOT A CLONE, "is a link to nothing".
• The doctor's slot reading should say not-a-clone for it, so the two still agree.
• siblings.py is a family-root copy carried by digest, so every holder will see an upstream-changed row.

Tests:

• Add a dangling symlink to UNREADABLE_SLOTS (tests/test_shape_doctor.py, siblings.py: a file, or a folder make siblings cannot list or enter, at ../<Project> is NOT A CLONE, reported and left as it is, so the run no longer ends in a traceback at iterdir before the members after it are placed, and make park no longer ends in one over a folder it cannot enter (#735) #772's agreement test).
• Add it to tests/test_family.py's NOT A CLONE test.
• Both are WINDOWS_SKIP where symlinks need privileges.

Lands after #772 (#735).