feat(ladder): reconstruct nematode + earthworm with opponent-pair CAZ

[gnowgi]

Corrected CAZ ontology (G. Nagarjuna): a lattice node is a multicellular muscle-side region; a muscle is one side of a CAZ; a CAZ = one opponent pair = one DOF (opponency intrinsic, per morphology.py / v2 eval C1).

• experiments/nematode.py: three tissues (passive skin+transducers, passive gut w/ no muscle, detached longitudinal muscle in 4 quadrants). CAZ = dorsal (+) ventral longitudinal (DV bend); cuticle/hydrostat = passive restoring; NO circular. Mouth = radial (+) elastic; anus = DV pair. Demo: anti-phase DV wave -> dorsoventral undulation. Sourced (WormAtlas).
• experiments/earthworm.py: two disjoint muscle tissues (circular segmental (+) longitudinal continuous), coupled only via coelomic hydrostat B_i + ganglia. CAZ = telescoping (circular (+) longitudinal -> peristalsis) + lateral-bend (left (+) right longitudinal -> turn); NO dorsoventral pair (that is a leech/slug rung). Sourced (Britannica; Fox/Lander Lumbricus).
• docs/ladder/opponent_pair_caz.md: the ontology + per-animal opponent-pair table + the cnidarian inter-layer 'neither DFN nor IN' caveat.
• experiments/caz_coordination_audit.py: the audit figure.

Both models self-contained; print their tissue/opponent-pair structure.

Claude-Session: https://claude.ai/code/session_01BZprhzZ5T5qBAoRB9yD1D5