dl: Free::fold anchor sets — Rem 2.13 vs Ex 2.12/2.14 + Prop B.18 on one surface

[tsondru]

One surface carries three CDL anchor sets since #310 (PR #378): the crate-wide "CDL Remark 2.13" catamorphism anchor (23 matches / 12 files, rg -c 'Remark 2\.13' catgraph-dl, incl. free.rs, free_monad/mod.rs, THEOREM_MAP) vs the new tree test's Ex 2.12/2.14 + Prop B.18. docs/2402.15332v2-AUDIT.md:133 scopes Rem 2.13 to list initiality. Decide which anchor the fold surface cites and unify.

Raised by falsifying-review rounds 3+5 of PR #378; owner-deferred at G9-T1 close (2026-08-31).

[tsondru]

Decision (owner-delegated, 2026-09-08): Remark 2.13 states the uniqueness for lists (2402.15332v2.md:241), so the generic Free::fold sites cite Def A.2 initiality with Remark 2.13 for lists and Ex 2.14 for trees; tree-direction sites cite Ex 2.14 / Prop B.18; list-direction sites keep Remark 2.13. PR #443.

[tsondru]

Landed: PR #443, squash a19a40d.

[tsondru]

Closed: PR #443 (a19a40d) — the generic fold sites cite Def A.2 initiality, Remark 2.13 stays on the list instances, Ex 2.14 on the tree ones; in v0.20.0.