feat(Studies): Dalrymple-Kaplan 2000 feature indeterminacy

[hawkrobe]

The frontier consumer flagged by the morphology audit: set-valued features and union resolution, read from the primary text.

• Indeterminacy as membership checking: German was/wem and Polish kogo/co contrast sets; the §3 refutations (underspecification forces NOM = ACC; every disjunctive resolution fails); verb-side sets (Xhosa, kaufen).
• Resolution as union over marker sets ⊆ {S, H}: full Fula table, collapsed English table, José y tu minimal-model derivation; Sag-et-al intersection refuted per §6.5; the De Morgan duality (102–103) is Finset.compl_union; Hindi/Icelandic/Slovene gender tables incl. CONJ-contributes-F.
• Refinement certificate: the flat slot order embeds into the superset-ordered indeterminacy lattice (flatLE_iff_toIndet_superset, none ↦ univ) — set values refine, not replace, the flat layer; bridge onto Features/Person.lean with the inclusive/exclusive collapse explicit.