Minimal Complete Support of the Terminal Ordered Residue

Theorem 18 established that the terminal ordered residue Ω_term is forced onto the active slot Λ₄ = (F₇, F₆, F₂). Theorem 19 strengthens this: Λ₄ is not merely the forced terminal slot but the minimal complete support of Ω_term. Every proper sub-support (all three single-family supports and all three binary supports) is eliminated by independent structural arguments. F₂ is necessary for local defect anchoring at the terminal closure event; F₆ is necessary as the linked transport carrier without which Π_pair annihilates the residue; F₇ is necessary as the ordered lift without which the support collapses to Σ₄, which cannot carry the orientation-sign invariant σ_Γ = −1. The triadic structure is irreducible: no pair of roles is sufficient, and removing any one does not strengthen the remaining two. Together with T18, this establishes that the terminal anchor is both uniquely determined and structurally irreducible.