DCRP57: Isotropic Residual, Straight-Cylinder NO-GO, and Twist Tail

Building on the two normal forms DCRP56 produced — the rank-three covariance and the cylindrical tail — this round checks each in turn using DCRP38's proper vorticity-covariance ledger and DCRP30's DSS sublinear energy-growth law. Substituting B=ρI into the ledger proves that the isotropic rank-three branch is not a zero-defect equilibrium but must continually pay a residual R_B=[ρ'+(2−3γ)ρ]I−2ρA, whose per-period norm is bounded below in proportion to DCRP56's ρ≥Z_in/2. It further proves that a globally straight cylindrical tail contradicts the DSS sublinear velocity-energy law, giving a NO-GO, which restricts the tail's only possible surviving forms to a twisted cylinder or an affine-hinge transition chain. STOP-D57 hands to DCRP58 the task of analyzing the coupling between pressure/PFET and the twisted cylindrical tail, to determine whether it can be excluded entirely.